Hi and welcome to the forum.
I'd second everything that has already been said, apart from Limecc, he's just anti SIB
(only joking
)
especially Jeff's understatement "in sea lochs it can get rough"!
We got caught out in Loch Hourn last year
https://www.rib.net/forum/f50/glenel...urn-86218.html
If at all possible, I'd try and organise a couple of trips out with someone with experience in their SIB before heading out on your own.
I'd also try a few trips from a beach (maybe not Morecombe), tidal river or an estuary, calm sea, sunny day, potter about close to shore. It will help you gain a bit of experience on moving water (albeit calm moving water) currents, tide times etc