Can I drop out of uni and have a chance to study at KCL?

Yes. I don't see why not, providing you have the A - Level grades, but please try to pass this year as you'll be in more debt if you do four years of university rather than three.

Im currently a first year student studying law with politics and I hate it, i have a clear preference for politics where I tend to average 70% while law i always fail.
I had an interest in studying european politics at kcl since i started feeling more homesick and depressed about my course and they said they could take me on for a transfer if I pass this year, but it looks very unlikely to pass as I've had many outside circumstances that make it very hard to catch up.

Do you think they could take me on if I withdraw as a student at my current uni and apply for September 2023, seeing as they also have room for transfers maybe that could be an option? Im not too sure how it works
thanks