Rail pass or individual tickets.

Have you searched National Rail for your trips? Including with railcards? Go to http://m.nationalrail.co.uk/pj/home if not. Click on the Journey planner. Go to the bottom and click on Fare options and indicate your preferences as well as whatever railcard you might qualify for. Choose Show only direct trains to get those without any train changes.

I can't imagine why you'd take a night train from Penzance to London when that trip from Penzance to London is 5 to 5.5 hours, no matter when you go -- except on the sleeper which takes about 3 hours longer and costs many times more even without a railcard.

Prices vary depending on the specific train and whether there is a change or not. I looked at advance fares for direct trains with the date of 28 September. The cheapest one way with no train changes is £23. If you can get a railcard the price should be about £15.20. All these trains end up at London Paddington.

For Birmingham to Penzance, you can pay £46.65 with a railcard . This is also for the sample date of 28 September and for trips with no train changes.

Those are some examples. If you can get a railcard, by all means do it. It will save you lots of money. Be sure to check online to see if there's a railcard for you -- http://www.railcard.co.uk.

Unless it's different for Canadians, you can only get a railcard in the UK. But you can order your tickets with the railcard factored in online. For my trip in May-June this year, that's what I did. I started the train part of my trip in Bath. I reserved tickets online at the earliest possible time I could from home. It was a 6 week trip, so that was a rolling timeline. I bought my Senior Railcard in Bath and printed all my tickets there. It was lots of work, but it was well worth the effort because it all worked without a hitch on the ground, or maybe I should say on the rails.

Foreigners can purchase a rail pass - when not in Britain :>http://www.britrail.com

However, most people reckon that despite it being more convenient, that the cost is much higher than pre booking specific train advance tickets - or pay on the day for short journeys. (Even paying the day before, will save money on longer trips).

I just did a check of some of your journeys for an assumed date of 11 October. I found that I could get from Edinburgh to Birmingham (on Virgin Trains) for £21 by splitting the tickets at Preston. (Each leg was £10.50).

I then did Birmingham to Penzance and got this down to £37.50 with 3 tickets (2 splits). So, Birmingham to Cheltenham = £7; Cheltenham to Taunton = £13 and Taunton to Penzance = £17.50. (These prices are without a Railcard Discount - which would give about another third off but the card would cost £30 - if you are eligible).
So, you work out what you can do the trips for on your dates by pre-booking and compare that to a Britrail Pass.

I suggested the BritRail Pass since you seemed to be worried about committing to specific departure times that worked around your other plans. Timing was close. The version for 3 travel days in a month would cover your three longest trips for $255 US for an adult, which seems like an easy choice to me, given the costs you've quoted. Sleeper fee would be extra. For delivery to a Canadian address, see www.raileurope.ca.

So at $255 for 3 days (plus shipping) is $85 per day, or around £64.

A day for Edinburgh to Birmingham at £21 = Britrail loses by £43.

A day for Birmingham to Penzance at £37.50 = Britrail loses by £26.50.

That third trip had better be pretty expensive for the Britrail to be an overall winner - at least £133.50 or planning ahead wins (purely on money, not quite on hop on hop off - ness.)

Nigel, Tina has already specified the prices that she saw available - 41 and 71 pounds, presumably for her travel dates, though we still don't know when they are. Advance discounts are all well and good until she misses the train because she's tightly scheduled, doesn't know the region, etc. She's also probably spending more time or worry on fine tuning these advance plans than she really needs to do.

Many thanks for the helpful replies.

I do appreciate the suggestion of a rail pass, I don't think it'll be worthwhile. I'm told I'm not able to book the Penzance to London sleeper in advance and can only do so once in the UK (and there will be a surcharge for the sleeper). I don't qualify for a rail card, so that eliminates possible discounts on the tickets I need.

My travel dates are in late October and early November and will soon be open for booking train tickets. At this time, I can only price out tickets until October 25, I believe.

I've no problem committing to a specific train, but want to have my T's crossed and I's dotted before I purchase rail tickets.