Powerboat Level 2 is the qualification most UK hire companies, sailing clubs and marinas actually want to see. Over two days you learn close-quarters handling, anchoring, man overboard recovery and enough navigation awareness to drive a small RIB safely in familiar waters by day.
Complete beginners are welcome, though many candidates have already done Level 1 or spent informal time on the water. The course formalises habits your uncle may have skipped: kill cord, lookout, and planning your approach before you commit.
Successful candidates can apply for the International Certificate of Competence (ICC), which hire fleets abroad often ask for. Wear the kill cord. Instructors mention it until it becomes reflex.