If you are a member of one of the two big clubs there are a few 5 van sites in the area, I think there is a commercial site just off the A34 south of the M4 as well. If we knew what your outfit was we might be able to come up with some better ideas.
Hi
Is this for continuing on the A34 or M4?
Not far off the A34 on the A4 there is a layby at Halfway (place name). This might be alright. It is a few hundred metres past the Halfway Inn on right hand side (there is room to turn round into it). Take the A4 towards Hungerford.
Amazing family weekend with old steam engines, classic car displays, market stalls, and full catering and bar. And camping on site - Save £25 by booking in advance.