Salamualikum.
If you know it's a sin then why act upon it? Remember is this gyal going to be with you on the day of ressurection answering for you towards you Lord?
Do you sincerly love her? or is fake love that happens at young age to many of us?
Why wreck your life and education? do you have a plan on what to do after G.C.S.E's? what do you wana do after your career? maybe talk to you local career and parents to get what there experinces are/were.
Don't give up at a young age, education is a precious thing and don't loose it. Many of us re-taking subjects that got low levels because we messed up in school. Well remember one thing the third person with you at that moment of time when mingling with opposite sex is satan. As a muslim aren't we suppose to fight against satan? Does or does allah subhwnatallah not say To stay firmly away from opposite gender and lower our Gaze? Yes. it's hard to act upon it but getting into Janah is hard aswel not easy, so it's bound to be hard.
Follow the sunnah, be good and take it easy inshallah
Ma'assalama
