My DD did some modules from this course in Medical Ethics, run by the Norwegian Medical Association: http://www.wma.net/en/70education/10onl ... /30ethics/
It used to be associated with a Norwegian university but the interface looks the same. There is a list of free online lectures here http://www.openculture.com/freeonlinecourses
but I don't know if they are any good, you might need to have a hunt around! DD had originally intended to follow an OU course but the one she had been interested in wasn't being offered when she wanted to do it. OU modules are now more expensive since the fee increase, but the OU assesses the income of the student rather than their parents, so this might be worth investigating as a possible avenue for study during a gap year. Especially if the subject is something that needs to be kept in practice, as you mentioned.
As regards practical skills, it really can be a massive boost to the confidence to leave home able to cope with shopping, cooking, washing, etc. DD learned much of this during her gap year. She now shares a flat with five people who went to university straight from school, but is far better able to cope with living away from home despite not being much older than them, with an August birthday. She's had to teach them how to do a lot of things and her nickname is "Mum"!
Regarding whether taking a year out will affect chances of an offer - only the universities can answer this. However, if one of the purposes of the gap year is to save a nest-egg to help manage the living costs while at university, I would hope that admissions departments would regard this as a sensible and mature approach, especially as so many students struggle with their finances.