Hi from Spain.
A brief for inflatables:
No title needed below 15hp (less than 11.03 kW) and less than 4 meters.
Beyond that, authorization needed.
Because of cortesy on international laws, non-official (I mean, nonmandatory in Britain) RYA title should be enough.
Always: insurance, boat registered.
National flag on stern.
PFD 100 newtons CE certified (1 per person, specially beware with children; if boat is certified for 7 people, you should take 7 PFD...but I guess 1 per passenger is OK).
3 flares (beware with expiration date), signaling mirror, fog horn, medicine box, torch.
Anchor and line.
2 rowing pads.
pump and inflatable repair kit.
bilge pump (can be hand operated)
boathook, 2 mooring ropes.
If more than 3 miles from coast: VHF (and you should have a title for VHF). If more than 5 miles...well neither SIBs nor common RIBS are safe boats.
It may look too many things but I keep all of that inside a net tied at the bow.
Bow cover, cargo net, fuel tank in bow and ladder
Have a nice time, you are welcome!