Why?

What's the point? Why do we bother? Does it matter if I don't bother at school or don't go there at all?

Yes, it does. Let's examine this logically. You go to school. You get exam results. These convince people you are able to do something for them. They pay you to do it. You spend that money on something you want/need. You are happier.

So we start with going to school, and it turns out to be a way of having fun. Why not cut out the middle man? Can't we just start having fun now, without the bother of 15 years of education? No, because it turns out that you can't, because things become considerably less fun when you leave school with no qualifications.

However, it's possible to see that some things will not aid you in your pursuit of happiness. Some things will happen that you will be made to do, and they will have zero impact on your happiness. They will, in fact, make you unhappy. It's fairly easy to spot these things. One of them might be, say, a Biology GCSE. You may have no plans for Biology because you might not be any good at it. If you aren't going to take it for A-level, it doesn't matter to you. Why should you bother in it? You shouldn't. Unless you've got time on your hands, of course. Or unless you need to make up the number of GCSEs you have.

The point is, GCSE's are simply a passport to doing A-levels or GNVQs, which are in turn a passport to a university degree. When going for a job interview, the first thing an employer does is look at what degree you have (if any). If that's not quite up to scratch, they have a look at your A-levels, but they don't go any further backwards.. Not a single employer (of people above degree level) will be interested in what grade you got in GCSE Biology. It will not affect you. It will not matter. Especially if it was only that subject you flunked.

Alternatively, homeschooling is arguably a good idea, if you can stomach it.