What do you mean about stablecoins tho? This is new to me?
Stable coins like USDT, a coin with stable value ~$1, use Ethereum network, you can trade with them on probably all exchanges. Transaction going fast 5-15min usually.
Also, there are many exchangers where you can exchange fiat to USDT.
you can check my signature to find some of themI am not sure what is your first attention when you want to deposit money on the exchange, it is okay if you just want to buy cryptocurrency, but if you want to trade I would not exclude that easy exchanges with the largest volume of trading. it is very important for trade.
As one suggestion to you, because you expressed in £, check cex.io exchange, they have almost all pairs related to GBP.