Yes, student loans used to be repaid at Inflation + 1% but new student loans are now repaid at RPI + 3%. So yes, student loans are charged interest even while you don't pay them off.
You repay them at 9% of your income once you earn over about £21k now. It's still worth studying even with student finance. You'll be earning no more than £15kpa with no qualifications, easily upward of £21kpa with them!