Is Competent Crew for complete beginners?

Yes. RYA currently lists no previous sailing experience as a requirement for Competent Crew, and the course is written on that assumption.

It runs over five days, normally liveaboard on a cruising yacht, and it covers steering, sail handling and changes, reefing, ropework and knots, safety equipment, person-overboard recovery, basic meteorology, keeping a lookout and the general routines of living aboard.

What it is not is a skipper course. The purpose is to make you an active, useful crew member who understands what is happening around them — someone a skipper can give a job to. Taking charge of the boat comes later, at Day Skipper.

It suits beginners heading toward yachts rather than dinghies, couples who both want to be competent, and anyone whose end goal is charter, ownership or offshore passages. If you only want to try sailing once to see whether you like it, Start Yachting is two days rather than five and costs a good deal less.