Time to buy train tickets - now or wait?

1) Edinburgh to GQS- Just a walk up fare. No benefit in pre-purchase. Just take the Falkirk High route, which is the most frequent. Personally if going to GQS and I had a choice at the same time I would take the newer Bathgate route, but keep it simple. Take whatever is the first train out. At GQS the Falkirk High trains use the High Level Platforms (in the main train shed), the Bathgate trains (which continue to Helensburgh use the low level platforms;
2) EDI to Haltwhistle- half a dozen of one and half a dozen of the other as to whether to go via Newcastle or Carlisle.
The best fare I am seeing is the 0852 via Carlisle- £16.40 each before railcard discount. That will get you there by 11am- is that too soon?
3) Haltwhistle to Keswick- I would say take the bus via Carlisle, BUT on a Sunday that is a 2 minute connection. So get a train single advance fare at 1100 for £3.60- arrive 1134 at Carlisle.
Then the 1200 Service 554 Bus from Carlisle Bus Station, arrive Keswick 1315. £2 each under the Government Flat fares scheme;
4) June 21-
Bus X4 or X5 from Keswick to Penrith Railway Station at xx20 (from 1020 onwards) arrive xx58 £2 each. Take the 1222 from Penrith to Crewe , a 1400 - £13.60 Advance Fare. then the 1445 to Conwy (change Chester, arrive 1623) on your pass;
5) June 24- Take the 0917 direct from Conwy via the Welsh Marches, a 1315- on your pass-
6) June 26- Take any train- I would just book that as a ticket from Swansea- for £50.50 each, from Cardiff it is still £47 and from Newport £43, so very little obvious benefit from booking part as pass and the remainder as a ticket.
It's your choice whether to buy as virtual tickets or as physical tickets picked up from ticket machines.
I am actually sceptical, if the above are the totality of your plans, as to whether the Explore Wales actually pays for itself.

one each

I manage totally adequately without any apps at all, and have physical tickets. Very rarely on Northern services, when totally forced to, I will have e-tickets, but never m tickets.
I didn't need an app today to dynamically reschedule when one train was cancelled, and the next one delayed- just a good dose of common sense seasoned with a dash of good luck. Out of that heady concoction I ran 45 seconds behind schedule.

By the way no train from North to South Wales will ever be non stop- direct (as in no changes), yes, non stop- no.

Edinburgh to Haltwhistle: Yes. 0852 is too early. We are going on a tour of Hadrian's Wall the next day so we don't need to get there that early. I thought about stopping along the way, like Newcastle, (or any other coastal town), but we will have our luggage with us. Would getting off the train, even for lunch be worth it? Otherwise it comes down to time in Edinburgh or time in Haltwhistle ...

As for the Explore Wales pass - we can also use it for day trips from Keswick and/or Conwy for area sightseeing since we won't have a car. Any thoughts?

Well you can't use Explore Wales for day trips from Keswick as Keswick isn't in Wales.
But from Conwy you have a couple of days when you could make good use of it.

What I would do for Edinburgh to Keswick is that, as it's such a short journey, is I would break the journey at Newcastle or Carlisle. There is left luggage at Newcastle Station -so you aren't seeking out someone like Stasher, Radical Storage etc.

EDI to NCL there should be three or sometimes four trains every hour between the 4 operators- LNER, TPE, Lumo and Cross Country.

If I was booking for this morning now the advance fares for today EDI to NCL (available at 0750 for after 0930) are barely more than they are for 16 June. Maybe £5 to at most £10 a person, even less after 2T discounts. So book an advance fare as you eat breakfast!
Trains are every 30 minutes Newcastle to Haltwhistle. So just pick a train mid afternoon before the busy period after 4pm. That gives you good, useful time in NCL.

For NCL to Haltwhistle get an advance fare for 16 June today, it'll cost £4.50 (or £5.80 for 2 people on 2T), book an hour ahead for today it's only £8.70 2T, 2 people, advance fare). Book that on your phone on the way

This is a journey where going with your heart and the weather, more or less on the day, makes barely any financial difference, in the overall scheme of things.

How you buy your ticket is your own personal choice. But I'd like to tell you why I try to buy my tickets either online or via the app.

Cancellations or Delays.

The UK has an excellent refund system where if your train's arrival is delayed by 30-60 minutes, you get a 50% refund. Over and hour and it's 100%.

Unfortunately, this has happened to me too often. By buying online or via the app, I usually receive an email from the train company saying I am entitled to compensation and all I have to do is click on a link to get it. No need to send anything in or fill out a lengthy form.

If you do decide to go the online route, I'd also suggest taking a screenshot of your ticket in case your phone acts up when the conductor comes around.

It's also not necessary on commuter routes or frequent ones where the fare doesn't change like Edinburgh to Glasgow.

The Explore Wales Pass will allow you to hop off and then back on later trains when going from Conwy to Cardiff. (The train frequency is at least hourly - though try and avoid Sunday travel). I would suggest that you might like to ‘hop off’ at Shrewsbury and Ludlow when doing the Conwy to Cardiff journey. https://www.ludlow.org.uk
https://www.shropshire-guide.co.uk/places/shrewsbury/

If using the train for the 21 minute trip from Cardiff to Caerphilly (castle), you might wish to pay the fare at Cardiff station as it is only £5.45 each return rather than use a day of your Explore Wales Pass. The Cardiff Bus (32) fare to St.Fagans will also be very cheap.

QUESTION: for the first reply by @isn31c, what resources/website were used to find the buses and trains? I am trying to learn how to piece together a similar trip. Thank you.

For MJ- an awful lot of personal knowledge and experience plus judicious use of train planners-
For Journey 1- use any rail planner. I personally use Northern Rail for most things, but National Rail, or LNER or any other will do the trick. I just swear by Northern Rail as being really intuitive. I also have enough experience and knowledge to know when sometimes the rail planners "throw me a doozie". You either do or don't know the layout of GQS platforms. As I said keep it simple and use the Falkirk High trains which is what any planner will throw at you as 1st choice. There are several other routes- that adds too much confusion.
Journey 2- again knowledge. My preference is west coast (always cheapest and should always be fastest), but in this case I am pleased the OP gets to do a full Tyne valley line transit by going down the east coast, then the next journey complete the line to Carlisle. He had a specific request- not to be too fast;
Journey 3- Here the OP asked a very specific requirement. You could plan that on traveline, I have the old fashioned paper schedules and town/city knowledge to give a best answer. The usual answer is to route via either Penrith or even Workington by bus or train- which are more frequent routes, but the question was minimise transfers and travel time. Most folk reject the 554 bus out of hand out of prejudice and/or ignorance.;
Journey 4- Again the OP had a very specific request, so use a mixture of knowledge and the rail journey planners. If he had asked fastest route the answer was probably change at Warrington, if he had asked cheapest route the answer was likely Crewe, but catch a forward train about 30 minutes later. Some of that comes from simple playing around.;
Journeys 5 and 6- are just simple train planners. On Journey 6 I didn't know, but suspected the answer about whether to use Explore Wales, so just fiddled about with the rail planners- for the 3 relevant fares- ex Swansea, Cardiff or Newport (Gwent).

Briefly I treat every questioner as a personal friend and answer accordingly, from a vast pool of personal experience, backed up by checks. I give vastly more time and effort than is strictly justified often, and quite frequently get abused by other forum members for doing so.

For ian31c: thank you, this is very helpful.

I admit to being baffled by the array of train companies and bus companies, and am often frustrated when looking at online rail planners (thank you for the Northern Rail tip). I generally do NOT want the fastest or least expensive trip but rather want to do a specific journey on a local train through a scenic area. Without a paper Thomas Cook Timetable or equivalent, I struggle to find the trains and routes I want.

For buses -- Traveline? Again, balancing time vs a scenic or interesting route is the goal.

Again, thank you for taking the time to explain (and apologies to tvlrPhil for taking his question on a tangent).

This is Traveline England, this is Traveline Wales/Cymru and this is Traveline Scotland

Thomas Cook paper timetables are much missed- I still use them all the time for guidance. My other paper source of UK bus timetables is the long out of print Great Britain Bus Timetable- it is still the best possible nationwide guide out there, which I can easily update- not so much through traveline but through operator's own websites.
I use that at least weekly, for my own travels- let alone this forum.

MJ - No need to apologize! I suffer from the same difficulties that you described. Trying to learn to use a single train website, let alone a whole country's rail / bus system is difficult and often frustrating. I feel very fortunate to have the benefit of isn31c and others' expertise - not just the straight schedule and pricing, but also all of the nuances that they offer! I finally downloaded the LNER app to my phone and will probably try to download the Wales app.