The NHS (National Health Service) is the Official government site for health services in the UK. They offer a range of help and you can even call 24/7 for nursing advice to NHS Direct on 0845 4647. In their website they give you plenty of advice on their minor self-help guide.

There are a few hospitals where you can access free of charge their emergencie service (dial 999 to get an ambulance). In Britain, you can be hospitalised and treated free of charge as an emergency patient regardless of your nationality.

Only if you stay in the hospital for over a night, you may be asked to pay later for the treatment if your country hasn't got a reciprocal health agreement with the UK.