I think there are exchanges who exchanges who really accept GBP deposit via specific payment network and one of that is Binance. You can directly trade it with couple of pairs such as BTC, USDT, ETH and many more but it's only in spot. You can't be able to trade GBP in leverage trading in Binance.

Aside from that, you can't find all the information you need to deposit/withdrawal about GBP here in this link: Deposit and Withdraw EUR and GBP via SEPA and Faster Payments Service (FPS)