bananasarecool, if you are in the UK and you are worried about going to see your GP there is a family planning clinic specifically for teenagers, I think it is called Brooke. It is a confidential service. They are happy to give advice and free contraception.

I personally feel it best to use the pill and condoms. The pill is not 100% effective, takes a while to get in the system and doesn't work if you are sick. Condoms are not 100% either so if you use both that would make sure you are protected against pregnancy and disease.