The only way I know at this time is buy some other coin or a stable coin (coinbase works last I checked) and then trade into hive on binance or the likes.

Bittylicious is also good, it acts more like a peer to peer market for crypto than an exchange and is usable in the UK still. https://bittylicious.com/

There's no direct method of buying hive that I know of available in the UK and even getting normal crypto is a pain since binance nolonger does UK fiat payments