Thanks to a contributors comment I was able to get in to a campsite nr Sandbanks beach.
Beacon Hill Touring Site - its got "mixed" reviews on uk campsite (chavs - dirty toilets - none of the good neighbour rules enforced) .... so was a bit wary having read those after booking but decided as just one night would risk it.
Absolutely fine and no problems.
Arrived about 12:30pm After setting up the awning and new inner tent we visited sandbanks beach on the afternoon 1st day - cheated doing dinner by having pizza express and a walk round the nicer parts of poole quayside area.
Next day off to Lulworth cove - morning on the beach there - then walked over to Durdle Door beach and back along the beach way to Lulworth.
Glorious weather - and a lovely start to the yr..
Durdle door

My family and the camper

new inner tent
