Have you got a chartplotter and depthfinder? These are terrific pieces of kit that give loads of aid and confidence when out boating. Obviously these are Aids and should never replace your eyes and senses, but will give you information on areas that you can go in safety and areas you should keep clear of (Bramles Bank when setting a course for Cowes
The other items you should have are lifejackets, VHF radio and Flares. You never know what's going to happen out there (I guess I'm teaching you to suck eggs
but this needs to be said).
One other piece of kit which is handy is a Phone in a waterproof bag. Have the coastguards number programmed in. Seastart is also handy too!
What I'm reallly telling you is to cover all the bases, but experience is what you're after and will count most highly amongst essential items needed onboard
I haven't been to the Island this year, but many people do every weekend as suggested.
Perhaps you could start a "cruising buddies needed" thread in the RIB cruising section and see how you get on.