Look out for...
MMM runs (ive done 3 of these now, great fun
)
Cotwolds run (ive done 2 of these
not sure if there is one again this year? Bob?)
Chilterns run (never done one but one might crop up sometime soon)
Ohh and there is a Herts run organised for the start of June if you are interested
But there are plenty more if you travel a bit further afield