$immo is correct. I worked on a construction on the sea front and vans are a no no, at certain times of the year. However there is loads of free parking on the roads adjacent to the sea front. Just be careful, some are residents only.
Stayed at lytton for a couple of nights whilst working there. We were warned not to get a pitch close to the road as it is very busy at all times. We requested a pitch away from the road and they were cool about it. Decent clubhouse, small park for the kids.
Swanage is nice if you get the weather.