It’s hard to make A Level choices when you are unsure what you might want to study and/or have no idea what careers you are interested in. Try not to think about A levels entirely in terms of university - instead consider which subjects you actually enjoy and do well in, as these will feed into the subjects and types of degree you can eventually do.
A levels go into more depth on a smaller range of topics than GCSE, so you need to be sure the subjects you choose are ones you will be excited to study for two years - even though there may be one topic in the mix that you like less than the others. There’s no point studying history if you hate it.
The starting point should be to look at your predicted grades for GCSE at the moment - are they strongest in maths/science, or humanities/arts? Does your 6th Form offer subjects you’re interested in but never been able to study at GCSE - Psychology, Economics, Business studies or Computer Science, for instance, can be great to add to the mix.
My son had no idea in y11 and , after a bit of a disaster with GCSEs, he ended up doing Maths, Physics and Economics. Wasn’t much fussed about maths/physics by the time he did GCSEs, but it was the only A Level pathway he was allowed on with his grades. He was told he had to do economics or a BTEC in engineering as the 3rd subject. He chose Economics with no expectations.
In the end he really enjoyed economics, almost considering doing it at uni, but actually fell in love with Physics in a way he hadn’t had the chance to at GCSE. He’s now doing an MPhys in nuclear astrophysics. Two-three years ago he had no idea what this was, but he went in to A Levels open minded and with no idea at all what he wanted to do with his life.
So I’d refer you back to: which subjects are you doing well in and enjoy? Start there.