In regards to the cashback aspect of saving here is the link to Sign Up: www.topcashback.co.uk/ref/ciarangally You'll also be able to get a FREE £10 just for signing up - Which is payable once you earn £10 cashback. As well as saving on train fairs you can also use TopCashback to save money on flights & hotels too along with many other things :)
Visiting UK in December > just started booking train tickets as I'm travelling between London to Liverpool, Liverpool to Wrexham, Liverpool to Edinburgh and finally Edinburgh to Manchester. Bought the Family & Friends Railcard (£30), already paid itself for our London - Liverpool trip. Now trying to plan the other 3 train rides > contemplating using Trainline or TrainPal apps > as buying off Avanti is scary expensive.
The National Rail website is also a good place to check as that usually means you can buy them directly off the independent train companies - www.nationalrail.co.uk/ If you can buy them directly from the train companies that’s what I would advise as most of the time that's how you get the best price, and if it comes with a cashback deal as well that's of course an added bonus. Enjoy your trip to the UK!