Can't disagree with anything robin has said. The £14 landing seems good seeing as residents pay £9 and £2.53 for parking looks a bargain. I don't think the clubs will save you much.
As Robin says, the southside is better for taxis and the tower, so you'll be either parked on the disused or the grass. You only need one Hi-viz betwen the two of you.
Robins route is very nice but doing the Needles to Sandbanks, I would want a vest on. In my 172, its around 15 mins.
PM me if you want to know more.
-bcfc