Two Together Railcard or Not?

Yes, a two together railcard will save you money over these three trips.

You need to do the research on this by using the National Rail website and including that there are two people using a two together card in your original search. Train prices vary on these routes depending on the time of day. I like your idea of splitting the Dover/London/Edinburgh trip to save money. However, you need to look up the times and trains that are specific to your purpose. Be sure to leave enough time to go from one station to another.

Aah, you seem to have run into the split-ticketing situation. Very smart of you to have discovered that before you bought overpriced through tickets. I don't see any reason why the Two Together Railcard discounts wouldn't apply to the £171 fare.

You are planning significant rail trips. I think the card will help you a lot, but I trust one of our UK rail experts will respond soon with a definitive answer.

Don't know what and when tickets you are looking at.
The cheapest tickets are called Advance Single where you have to travel on booked train. If you can't see these you are looking too early
For example i am seeing a Dover to Edinburgh Advance Single of £56.00 in June. You can get about third off this with a Two Together Rail Card, the cost for two would be £73.90 (Standard Class)
Suggest you consult www.seat61.com for information on rail travel in UK including how to book tickets from abroad

remember that Two Together isn't valid before 9:30 M-F, otherwise yup, valid on all those.

Careful about running into the lovely, everything's wonderful Grant Shapps' "Great British Fare Sale" for only a million "Advance" fares until the end of May. It may skew the fares you will for a test booking for July. They may be available for your specific journey, but with the uncertainty around us do you want non-refundable fares this far ahead?

Pre-covid we had about 1,800,000,000 passenger journeys per year, so about 5 million a day. So just one million in the sale shows that you may or may not score a sale ticket, but what you see on a dummy booking may or may not reflect that...

You don't need the Railcard in your hand when you book tickets, just when you go through the gateline and on the train when the Senior Conductor/Conductor/Ticket Inspector/Train Manager/Guard/Customer Experience Ambassador (that's for the lumo crowd) comes around to check tickets. Those titles are used by different companies to mean quite similar jobs, looking after the safety of the train and people onboard, and ensuring passengers have the correct tickets. You may run into any of these titles on the various trains. Only lumo uses the slightly pretentious Customer Experience Ambassador, the rest have traditional titles.

EDIT - a correction to the Great British Rail Sale - the correction is the sale period, until the 2nd of May, for travel until 27 May 2022.

I think you are looking too soon for the unreleased cheaper tickets, set up an early bird ticket alert, a quick check shows those initial prices you saw £376/278 were for Anytime single tickets flexible but pricey, as mentioned you need the Advance ticket product, non refundable, specified trains only.

Beware travelling at weekends/bank holiday (10 July is Sunday) there is a warning marker on that timetable route about possible unconfirmed engineering work, replacement buses are used but it all makes for a longer journey time.

Defiantly do split ticketing e.g. on July 10th

Dover to St Pancras Super Off-Peak Single ticket £48.80

London to Edinburgh (depart 12.00) Advance ticket £41.90

The above are for 2 people with a Two Together card

Thank you, OP... I was wondering about some of this... So, the Two Together Railcard can be used with Lumo as well?

The split ticket price is still dearer then the Advance Tickets i am seeing in June at £73.90
You can use Two Together Rail Card on Lumo

Thanks all! I will wait a bit before booking.