G-O-B,
Concur with all thats been said; you can go up to Walney island and have a shorter sea crossing from there, and follow the ferry route. If you go at end of May, it`ll be TT practice week and accomodation may be tight if you are staying-if you`re a biker-`nuff said; if not,worth watching a few practices on real roads.!
Also suggest you give Manx Flyers Aero Club a call 01624-825999,for a chat ,possible cheaper parking,servicing,car-hire,B&B`S,good food,pubs etc.
The weather can be very changeable btween N and South of the Island,due to the topography/hills. Jurby and Andreas airfields in the North can be used as bolt-holes if you got caught out,but are only open/available for home-based a/c and micros/gliders-not for normal arrivals-during TTpractice its used by racers for setting-up.
Sounds a bit biased? Of course ,I`m Manx!