STICK WITH IT
If you drop out:
What will you do? You're smart and hard-working enough to re-apply somewhere else, but then that's a year of your life gone *snaps fingers*.... As you say, gap in the CV, etc. = not good. Also, consider the rise in tuition fees, you'll be a new student so you'll get hit horribly by them (presuming that you get a decently paid job, which by the sounds of it you are easily capable of).
If you persevere:
The times where you really show your mettle are when you are tested like this. Yes, the work sucks. Yes, it's boring. BUT, how many people in the world would give ANYTHING to be a Chemistry graduate from Oxford. One billion people in the world live on less than a dollar a day. Many billions more have no hope of a "western" income. Cherish the opportunity you have been gifted. You might regret it years later that you didn't finish the degree, but if you just hold out for a bit longer then no-one can take that degree away from you!