Rules for beginners:
Go to ski school - no matter how good skiers "friends" are, they are not trained in how to instruct, and many good skiers find skiing so easy that they can't explain to beginners exactly what they should be doing. Get professional instruction. Instructors know how to teach. They know the safest places to go to and they know how to keep their students safe. In France, try to find an English-speaking ski school (NewGen, Oxygene) rather than ESF, whose teaching methods can be a bit of a culture shock for some Brits.
No skiing with friends after a liquid lunch or apres session, or after lunch if the morning lessons have been tiring. Friends are generally not good at assessing which pistes a beginner can manage (they possibly won't have seen them ski anyway if they have been in ski school) and everyone's judgement can be impaired after a beer or vin chaud (or three).
Get fit before going - or at least do some stretches, lunges and squats, and some sessions on a static bike or treadmill ... see the current thread here on MN about getting fit.
Rent the correct, modern equipment from the ski hire shop. Don't make do with friends' old skis and boots - there's a reason why these have been consigned to the back of the locker, either they are worn out or unsafe, or both.
Wear the right clothes - beg or borrow a ski jacket and trousers if finances don't stretch to "new", but buy ski underwear, proper ski socks, fleece, gloves, buff and helmet. Decathlon or Trespass do perfectly good stuff at reasonable prices and nobody can see that you're wearing £15 Decathlon long johns rather than the £195 hand-spun mongolian virgin yak-wool thermals with a fancy brand name.
Most important - look good and have fun.
As for risks - the part of the holiday with the greatest risk is probably the journey from the house to the UK airport.