Hey you're picking almost the exact same subjects as me to do the exact same degree (Psychology degree)!
Im going for English Lit, Psych, Sociology and Economics. I haven't done the last three at all either, but I feel quite confident with Psych and Sociology and Economics will be something quite different to the others (involving some maths)
I had the exact same issue with thinking that my subjects would not appeal to some unis. However, someone had told me that as long as I achieve A*'s in all of them, why on earth wouldn't they take me! Build up your skills and do work experience. Get involved with stuff that will enhance your chances of getting into a uni to study those specific courses (like the EPQ) I strongly advise you look up what uni you want to go to and look for the entry requirement because for me (for the life of me I cannot remember the name of the Uni) but it said that Psychology is classed as a Science, and if it is picked the entry requirements would be lowered. It also said that there are no SPECIFIC necessary subjects but I really do advise you look some up for yourself just in case.
I had switched from Politics to Economics because again, its just something different. But the topics discussed in Sociology in comparison to ones in Psychology and what I want to get into in the future are just too similar not to take up. Don't listen to your teachers. Yeah of course picking subjects you have never done is not gonna be easy but if you work hard then why not! It happens to lots of a-level students and it would be ridiculous to think that way.
I'm not a 'sciency' or 'mathy' type person as writing has always been my strong point. And if I force myself to pick something like Biology (which I don't feel confident in) in order for a Uni to maybe think better about my application, I could end up failing! Its better to achieve A*'s in 4 subjects you love than getting a B or C in a subject you don't/are only picking for uni. Think about it like that
I hope i've helped you out a little bit
Edit- If you truly decide to move to History or take up any subjects on your list, be sure to do some research. Check the new specifications. Look at past papers. See how the subject is set out and then decide if its for you
Edit 2- Just noticed you said you got an A in GCSE History? So did I! (we are actually in the same boat) But that was out of a whole load of struggle. \if you truly love the subject and see yourself doing well at Alevel then defiantly go for it.