In reply to mypyrex:
> Having been through the various websites(Trainline etc) the cheapest I seem to be able to get(with railcards) is about £450for the two of us(return).Does anyone know any (legitimate) tricks for getting it cheaper.
Number one way to save money on train tickets: don't buy through Trainline. They charge commission, and fees for credit cards, that the Train Operating Companies (TOCs) don't - in fact they actually aren't
allowed to. By all means use Trainline to research routes, times & ticket prices if you must, but once you've made your choice you will never be worse off buying through one of the TOC web sites, and you will usually pay less. (Any TOC can sell you any ticket on any route, though not all do. When choosing a TOC to buy from you may prefer to use one which awards Nectar points or other loyalty perks).
The National Rail Enquiries web site is the horse's mouth when it comes to querying the ATOC's motherlode of route & ticketing information that all vendors of train tickets actually rely on. Contrary to what Trainline's advertising tries to imply, they do
not have access to cheaper fares than anyone else. Given that they charge commission, they can never be cheaper than going through a TOC.
Apart from the above, other advice here is valid: wait for the cheap advance tickets to come available (and yes, you can use Trainline to get alerts without buying through them), and look at split ticketing. One warning with split ticketing: you are quite likely to end up with different seat reservations on the different legs of the journey. Depending on whether someone wants to take up their seat reservation on the second leg, you may find yourselves having to change seats or even coaches, which may undermine the "luxury" of travelling first class somewhat.