The best suggestion I can give you as a musician in Hull already in a group, is to find out when and where all the local sessions are. I know there are sessions nearly every night of the week in Beverley and some in Hull. Also it would be helpful for prospective accompanists if you state which genres of music you're interested in, what instrument(s) you play and what other combinations you are looking for. Are you looking for improving beginners or seasoned players? I think there is a folk club in Brid and I recently saw something folky advertised in Driffield.