All clubs I've belonged too (Forest of Dean and Chepstow have been welcoming to a wide range of abilities. The people I've met at races from Severn AC and Gloucs AC have been very friendly. Go along and give a training night a try. I'm sure they'll be a wide range of abilities and the coaches would be very welcoming!
How much sponsorship did you have to raise? I got a club place last year and decided to raise money for NSPCC got £500 with little effort and time but worried over hitting £1000/£2000 mark.