OK Neap - slowest current/Tidal flow
Spring - Fastest current/flow
Beginners = Neaps (safest), therefore in July either the 4th or 18th, Lulworth - Durdle door (probably far enough in small boats, good rockhopping potential)
August 1st - 15th - or (29th BH) fine weather Keyhaven - IOW, (bad weather Lepe - Beaulieu)
18th July Lulworth
1st Aug IOW
Are these dates suitable?