Repeating year 12 or gap year with extra A-Level

Hello,

I'm in year 12 and have been spending some time considering degree options. I've recently worked out I'll probably need to take a different A-Level to the ones I am currently studying to get onto my preferred degree, and I'm wondering what the best way of doing that is.

For some background, I want to study History and Politics but have taken neither at A-Level. Most universities require History for a History degree, even if it's a joint honours (trust me, I have a spreadsheet)! Not all do, but I'd be worried about sticking out to admissions staff as almost everyone else will have it.

I'm currently set to get decent grades with my current A-Levels (predicted A*AA). I really dislike two of them but I would also really dislike having to go through Y12 again...

I'd be interested to hear your opinions, especially if you've been through this before or know someone who has

Thanks in advance