It can be difficult knowing what subjects to choose at the age of fourteen. You need to think ahead and decide what career you want to do and then pick appropriate subjects. It can be a difficult thing for many young people to do. However, if you pick sensible subjects then you will have a good selection to enable you to take a range of subjects at the next stage.
It is sensible to have maths and English, a science, a language, a humanity and an art. It is a good idea to choose subjects that you are really good at and ones that you enjoy, which are likely to be the same things. Then you need to be sensible as well and get a good range of things.
However, stressing too much about your choices is not a good idea. There are many people that change their career and you may be among them. It is possible to do further study when you are older and get other qualifications. If you want a degree in a subject but did not do the GCSE or even the AS level, it may not matter It is likely that you will be able to do it anyway. You will need to have some qualifications though and so it is important to make sure that you work hard at the ones that you do choose. You will also find that most places will have English and Maths as a basic requirement and so you should take these subjects anyway.
So in conclusion take English and maths and also subjects you are good at and ones that you enjoy. It is best to try to get the best marks you can at this early stage. If you are equally good at everything or like everything or do not shine in any particular subject then get a good range of subjects and it will keep your options open for when you do decide what you want to do. Most importantly, no one is interested in your GCSEs when you are going for a job if you have other qualifications and work experience so there are other ways of getting noticed.