Stopover

Where please? Halfway or further north?  But either way UKCampsite.co.uk will give you just about all the possibilities in their campsite search section. 

Not sure of your route but Tewkesbury springs to mind.

Chapel Lane is just off the motorway and is a nice site and because of its size is usually easy enough to get in.

Chapel Lane is a very useful site although I am not sure they would be on that motorway from Dorset?  

You need to specify your route and how long into your journey you wish to stop.

M40 or Fosse Way route I'd suggest Chapel Lane or Warwick. M5 Malvern or Tewkesbury.

Plenty of CLs closer to the motorways than club sites, if they're your thing.

If your stopping for a break i thoroughly recomend gloucester services they do a lovely breakfast and have caravan and motorhome easy parking , plus a nice farm shop :) mrs bc