I can help with this as a chemistry student at Imperial and I completely disagree with Kinga12. If you want to enjoy university life go to bath that's the simplest answer I can give you. You will be surrounded by people who are at university to have a good time and people will naturally be a lot more sociable because of it. Imperial College is not a sociable university by any means and it's exceptionally hard work. If you want to achieve a 1st class degree you can expect to be working 40 hours minimum a week in first year and chemistry is regarded as an easier subject at Imperial as well. The difficulty of work goes up exponentially after first year as well. Also first year counts unlike most unis.
There is no doubt Imperial is a fantastic university and if you're truly passionate about chemistry and doing it as a career I'd really consider it. Additionally, if you're very ambitious and career-focused you'll be far better off going to Imperial as I believe it's the best university in the UK for graduate prospects (yes oxbridge can be better but there is far more of a significant career focus at Imperial than oxbridge from my experience). To put it in context a lot of the people i know at imperial have offers from the best investment banks, PhD programs, hedge funds and consulting firms going. Again this needs to be put in context though as if you can't keep up with the work load you won't have much of a chance of having the time to apply for jobs. You probably need to reflect on how naturally chemistry and maths come to you in this decision.
Finally the social life is hit or miss at Imperial. I know plenty of people who love it and plenty who hate it. There's a general inverse correlation between class of degree and how sociable you are. It's relatively risky.
My advice would be as follows: if you want to enjoy university, have a relatively relaxed time and get a good degree and make brilliant friends go to bath. It's the safe decision. If you're willing to take a risk and get the most out of imperial both academically and on a career front then go to Imperial. You could fly through, manage to be sociable, get a great job and have a good time but you equally could crash and burn and become pretty depressed which is really common at Imperial.
Just a side note I'm not an Imperial hater by any means. I'm a very sociable person and I work hard and find maths and chemistry comes very naturally so I've enjoyed it enough and I'm really grateful on the career side, however, I know I would have had a lot more fun at a different university e.g durham/bath/edinburgh