Have you looked in Yellow Pages?
I use a company in Sawtry (Cambs), no good for you but there are plants all over the UK.
Had mine done a few years ago now, really cheap as my place had no minimum charge.
Wedge seem to have plants all over the place. You will need to get the paint off first.
No, it was Wedge who did mine last year and they are a one stop shop.
They did my bulkhead and all manor of other parts for me last year. The price which included VAT, stripping and collection & delivery (50-miles each way) was £140 which in no way can be called expensive.