I cannot offer any advice on gliding specifically in the UK, but concerning gliding in general: Go for it! Have always been an avid aviation enthusiast, but flying myself always seemed unattainable and way too expensive. Then the love of my life arranged an introduction day at a gliding club for my 32nd birthday (member experience, one tow, one wichlaunch) I was immediately hooked.
Soloed that first summer and now four years and (almost) five seasons later I have my SPL, Silver C and have done so many things I would have never thought feasible. Met an interesting bunch of people that have become friends (and who don't feel i'm a weirdo for seeing the difference between a Spitfire Mk. V and IX in a eyeglance)
Many of the younger members of our club are professional pilots that all seem to agree that gliding is the most pure and free way of experiencing flight. There are no words to describe that first solo launch, first flight in a composite glider, first XC, first 5 hour flight, ... And the gliding community is really that, a community. Every time I have flown at a different field, the welcome has always been ridiculously warm.
The costs rules out a PPL for me for the moment, but being in a vibrant club (on an interesting field) I have tasted motor flying, was a passenger on a Piper Cub flight crosschannel to your shores, saw a P51 beat up our field while thermalling and so on and so on. If flying is for you, you'll never look back. Just my two (euro)cents 😉