So it turned out I do have a place on Bryan Chapman, sent an unsigned cheque like an idiot, but they kindly gave me a few days grace to send a replacement.
Good news! I made sure to look up on two or three different sites to know how to write a UK check (I'm French) and still ended up having to write another one because of a stupid mistake - but I realized it before actually sending it :)
So it turned out I do have a place on Bryan Chapman, sent an unsigned cheque like an idiot, but they kindly gave me a few days grace to send a replacement.