Hi, folks. OK, for my time in England, I will need three train trips, and an unknown number of rides on the London underground. The train:
1. Express (?) from Heathrow to London upon arrival.
2. We will be in London 7 nights, then plan to take a train from London to Bath.
3. Later in the trip, we wish to take a train from Cambridge to York. (Will have car in between.)
I don't know if I should I buy everything here before we go, or wait til we get there?
I have looked into the National Rail website, and admit to a bit of confusion. We qualify for the senior card, at 28 GBP each, but I cannot tell how much that might save over the regular fares. I don't want to buy the "cheapest" ticket, as it is non refundable in case we change our plans.

Any help would be appreciated. We leave for London in 4 days.

I used this site (a Fodorite recommended it. I then emailed him a few questions and he got back to me with detailed instructions. He helped me along in my planning. A wonderful resource! I hope this helps....

http://www.seat61.com

If you are not willing to commit yourself to the restrictions on advance tickets, there is no need to buy in advance. Just buy the off-peak or anytime ticket at the station.

The senior railcard gets you one-third off the regular ticket prices. Since off peak ticket prices for your two journeys (I'm not counting the Heathrow Express journey, since I don't think you can buy the railcard at Heathrow) total about £104, there would be a small saving by buying the senior card. You can also link it to your Oyster card,if you are using that in London, for more savings.

I THINK the consensus is that the Heathrow Express is more expensive than getting a car service like Justairports to travel from LHR to your rooms. We used them most happily. No luggage slogging--even if you're smart and travel light!

The site kelsy22 noted is very helpful.

Don't buy anything now for your travel in London. Just buy an Oyster Card or a weekly travel card when you get there. There are 1000's (ok, dozens) of threads on Oyster/travel cards/2 for 1 vouchers on this Forum so if you are interested/concerned with the permutations, search for that. But you don't need to buy anything for underground travel ahead of time.

The difference between Advance and walk up fares can be very substantial. This close to your departure date, though, you're unlikely to find the very cheapest Advance fares: it's almost certain that the fares showing now will remain available until 1800 on the night before the journey. Buying the day before, in your situation, is probably the best compromise between low cost and flexibility (You commit online before 1800, then pick up the tickets at the station just before travelling. If you've got a steam-age credit card without a chip, allow time for queuing at the ticket office)

You'll also find, especially on your London-Bath trip, a huge difference between peak and offpeak prices.

There are next to no circumstances in which the Heathrow Express makes sense for tourists (just about the only exception, unless you're in a tearing hurry, is if there's one of you, and you're staying at the Paddington Hilton). Tube or pre booked car.

For the effect of a Senior Railcard, click "Passengers and railcards: change passengers (sic) details" when the National Rail site shows the fare choices.

For London Oyster is always the best value... You can actually get the tube to London if you don't ahve a ton of luggage... as for the day trips advance fares are always going to be cheaper, today the fare is £54 and advance fares are half that so you def pay for flexibility!

I am about to go to London too and have been looking at the same train dilemma.

With a trip out of London to Bath, I have compared the days I want to travel with train v coaches. ON some days the coach is far cheaper and possibly better because it may have no changes.

I just had a quick look on the coach site that offers transport from London to Oxford - 6 days from now as an idea - for 2 people over 60yrs. The best price that day is a total of 8 pounds only! Cheaper than a train! That bus leaves London at 12:30pm and arrives in Bath at 4pm and is direct without changes.

the site I used if you want to compare a coach trip is;
http://coach.nationalexpress.com/

sorry, I meant to say London to Bath (not Oxford)

Thank you, thank you. I've just about come to the same conclusion; you folks have confirmed it for me. Will buy the train tix and sr. pass, when we get to London. But just not comfortable with the restrictions on the advance tix, (probably not logical). Rethinking the Heathrow express. Thanks for your opinions on that.
Thanks again, you guys are great!