Thanks for your advice, and the link to the einstein's post (although I think the mechanics of online sales is a bit different to in-person).
I think you're right about accepting payments in fiat from a payment processor being the easiest way to go about it. I wonder if bitpay or someone will begin to accept Steem. To be honest though, I'd rather just keep things in crypto if possible... Ideally I'd like to convince my supplier to accept it too.
I've just talked to my accountant and they say that there is someone else within the company who has got experience in clients accepting crypto, so I'll have a talk with him and see if he sounds like he is on top of it.
Personally I doubt they'll change the laws on crypto post-brexit, but it's over 2 years before that takes effect anyway.