I've been offered a once in a lifetime chance (for me)

A 28 hour trip to the Scilly Isles. With 2 days drinking while there. These guys are serious yachtsmen... Atlantic crossing etc.

I've never been on a yacht before. My question is, what gear do I need for offshore sailing? This isn't the usual coastal sailing.

I could ask the guys but I don't want to be pestering them with questions. Would a waterproof jacket (fleece inside) and same trousers? Footwear?
I almost collapsed with price of those offshore suits and boots.
I'm hoping to do this for less than 150.