Bishstreetkids is 4-14 and is Ofsted registered. Try looking on the council website - the schools normally give out a newspaper before each holiday which lists holiday clubs and activities -I think it is called Shine and it is also available online.
Contact Kaleidoscope nurseries. They have a branch called KOOSH who run holiday clubs as well as after school. Definitely OFSTED registered. I THINK they would take an 11 yr old. It's a good club, lots going on. I've used them for years.