With only £25k, I wouldn't buy anything more than I usually do.
I would still buy the best value tack (quality but not nessessarily big names), I would not buy my self a young flashy warmblood- I will still look for a bargain compact sports horse to have some fun with. I STILL wouldn't spend more on a horse than I do now (Just because you have it, does not mean you have to spend it) and then, with what is left, I would bank and use for paying for training/lessons over the next few years.
mmm,,, horsebox
gold food bucket for his lordship
lifetime supply of cortavetHA
underfloor heating, weekly pampering (massage and all the other necessites when you have 25K