They're massive in Ireland, but not very visible in England. They offer secure savings (protected by FSCS, same as banks and building societies, up to £85,000) and loans often better value than credit cards, lenders that advertise on the telly, and sometimes better than high street banks (depending on your situation). they will consider lending if you have patchy credit history.
They are local co-operatives, often run mostly by volunteers and all staff, volunteers, savers and borrowers are members and are eligible for dividends. Every town/ city has them - did you know??