
Most beaches at that time of year section some off for us doggy owners, though they are not allowed on some parts of the beach they are still allowed - if you follow me?
Anyway, I always go to either Dawlish Warren, Teignmouth, West Bay Dorset. Chesil beach dogs are allowed but it is all pebbles where we go so no bathers. Weymouth you have to go up the far end to let your dogs on the beach, as with most beaches in the summer. Oh not sure how far Lyme Regis is from you but we took the dogs on that beach one year, no restrictions I think? Can't remember now what time of the year that was?
Oh I'm rambling now LOL But I would say there are loads of places to take the dogs, when you find somewhere you like just ask them when you book, they will tell you :-)
Have you tried these sites?
http://www.holidaycottages.co.uk/or
http://www.edeswellfarm.co.uk/pages/cottages.htmlHTH