my daughter is planning to visit London, Edinburgh, stratford on avon,cardiff and around Nottingham, would a train pass be the way to go. The pass that you purchase
here before you leave
Nobody knows. You have do to do your homework. You have to price out the point to point ticket and then compare.
Walk-up fares on longer routes are very expensive, but tickets booked in advance online can be very cheap. For example, the walk-up 2nd class fare for London-Edinburgh is over 100 GBP, but an advance ticket can be as low as 12 GBP. Those tickets are for a specific departure date and time and are non-exchangeable and non-refundable. If your daughter needs flexibility in her travel dates, they won't work for her and a pass probably would be better.
The best site I've found for booking advance tickets is www.eastcoast.co.uk. The site accepts US credit cards and you can book tickets for all UK trains no matter which train company is operating them. On the right-hand side of the home page you'll see the current farthest out date for advance booking.
If your daughter is interested in traveling overnight on the ScotRail Caledonian Sleeper between London and Edinburgh, book well in advance here to get a Bargain Berth as low as 19 GBP.