Hi Bink - I have no direct knowledge of a program, but have had a look at some various parenting/child directories (it's the least I can do to thank you/your dh for all the help on the self employed thread) to see if there is anything relevant.
First, let me warn you, I'm rubbish at links, but maybe these web addresses can be of help:
www.kiddikicks.co.uk
www.littlekickers.co.uk
Both of these are for children up to 6, but they may be able to suggest something that will be suitable for your son.
I've also had a look at Time Out's "London for Children" guide and there's lots of things listed there under the "Football" section - might be worth a look.
Finally, under the "Athletics" section (does that mean track/field? if so, might not be what you're looking for), there is the following entry:
"If you kid wants to try athletics, contact senior athletics coach Maureen Jones (8224 7579 or 07956 807689) who organises "Run, Jump, Throw" courses during the school holidays at several tracks around London for 8s to 13.
Anyway, best of luck with it and hope this points you in some useful direction.