I was in the Carew in crowcombe the other night discussing plans for the future requarding Mountain bikers using their services.
They've 6 rooms(providing beds for up to 12), will provide washing/drying facillities and bike wash/secure storage.
It's a 5 min ride from the trails, with a bonkers fast run back to end a days riding, or a leisurely traverse from the bottom of weacombe.
For larger groups they would consider doing Buffet lunches and in the future an uplift service to get you back up top after food and beers.
Chipps stayed there during his visit last year and may pop up and recommend it.
Other place to try is the very friendly Hood arms Kilve, though it's a little far from the trail heads.
Or contact mary from the old coach house in Bicknoller , that may work out cheaper for a group.