My OH is riding at Orchard Cottage Stables and Im sure they have a 14 stone weight limit......1/2 a stone is nothing and there's a few beginners horses that will definately take him.
where abouts in Surrey are you? There is a fantastic riding school in Chessington/Claygate, it;s called old barn stables. Don't know what their weight limit is tho. If you want the no. let me know.
Weybridge Equestrian Centre now have a nice selection of big horses. Not sure if Weybridge is anywhere near you? Also Langshot equestrian centre in Chobham.