hi - well done for asking questions here - there are a ton of experienced boaters posting here and some good advice to be had.
I am just curious if you have someone in the boat with you or a mate with another boat that comes out with you?
Someone being out with you with another boat will certainly make your trip safer.
Nothing wrong in enjoying some wave jumping, know you and your crafts limits and you will have fun am sure.
If your planning on going out alone, in choppy conditions, and blatting about in a SIB trying to wave jump, I would suggest the following kit.
2) A lifejacket capable of turning you right side up if unconscious
If your wearing a dry suit, then something with about 275n of bouyancy
An Auto for sure, as Willk said, a Hammar firing mechanism will prevent
an accidental inflation if the jacket gets really wet, or the conventional auto system which can sometimes accidentally inflate if the jacket gets very wet.
Make sure it has crotch straps, a light and a spray hood.
3) Handheld VHF securely attached to your lifejacket with a lanyard
4) A PLB - registered with the Coastguard registry
If this is out of your budget, think about some pencil type mini flares, if you can afford both, thats great.
5) I would think seriously about a dry suit. Just remember the sea temperature around the UK isnt the warmest and if you end up in the water without suitable clothing you will get cold quickly.
A dry suit is going to keep you dry and with suitable clothing underneath, will keep you warm, and if your comfortable out on the water you will stay out longer.
I know...you only asked about a lifejacket, but
a lifejacket is only part of the safety kit, especially if your planning more adventurous trips.