Starting A level maths 4 months late?

Hi so im in year 12 currently doing biology psychology and history. Im hoping to go to oxbridge to do experimental psychology/pbs. My backup plan is neuroscience anywhere else. My a levels arent well suited for this as when i chose them i had no clue what i wanted to do so i just chose a broad range of subjects. However i only made this degree decision recently. My careers advisor said maths is well suited especially if im aiming for oxbridge as im competing with many people who wouldve chose maths, also some unis say u need two sciences and i only have one. My school is wavering towards not letting me switch history to maths but if they did let me, im wondering if this is worth it. I know its a hard task and im definetely not underestimating it, im predicted 3A* and got all 9s at GCSE so i wouldnt want to do anything that could risk these good grades, but good grades arent anything if i dont meet entry requirements. I do like history sometimes but the workload is so so much and im not even passionate about it enough, one of the main topics i really hate. honestly if i had a time machine i would go back and choose different a levels but i dont, so im just wondering what my best way forward is.
Just to add some more context:
I got an 8 at maths gcse after being stuck on a grade 5 up until late march, unfortunately didn't do further maths and I do have a lot of spare time to catch up if needed (im quite up to date with biology and psychology)

Hello I am not sure of if I will be of much help but I took a few gcses a year early including maths - got 95% and last part dragged me back form the full- after not really being a ‘mathsy’ person through school, I was ok just not the best. My point being I self studied it alongside my 10 other gcse subjects that I was doing in school and maths was by far THE easiest to self study , and I am now starting to self-studying the a-level to hopefully take it a year early because my a level combos might be bit much otherwise .
Nonetheless, since you seem very intelligent (congrats on the grades btw) and are quite caught up , I would say maybe start the maths content (lots of threads on Reddit on how - detailed methods- people took the a level late, alone etc and achieved AMAZING marks) I understand this is not the benchmark but your grades entail you are above the average benchmark and are aiming for that sooo… my advice would be stick with your current a levels as you are clearly doing really well and study maths independently to see if you have the potential for an A/A* in the first place.If you were stuck at gcse (quite the bit easier than a level, from my experience) it might be a bad decision to not meet the requirements for neurology , in terms of grades, and lose a potentially good history that could be useful in a better fitting job for you , if you swap them before being certain of your potential.
Best of luck- I hope it all goes well and that this was useful .

Hi thanks for this advice! My careers advisor did say that I can do maths independently and I am considering this avenue as I dont want to risk choosing it and getting a lower grade than I would do in history. Im definetelty going to do more research.

Hi so im in year 12 currently doing biology psychology and history. Im hoping to go to oxbridge to do experimental psychology/pbs. My backup plan is neuroscience anywhere else. My a levels arent well suited for this as when i chose them i had no clue what i wanted to do so i just chose a broad range of subjects. However i only made this degree decision recently. My careers advisor said maths is well suited especially if im aiming for oxbridge as im competing with many people who wouldve chose maths, also some unis say u need two sciences and i only have one. My school is wavering towards not letting me switch history to maths but if they did let me, im wondering if this is worth it. I know its a hard task and im definetely not underestimating it, im predicted 3A* and got all 9s at GCSE so i wouldnt want to do anything that could risk these good grades, but good grades arent anything if i dont meet entry requirements. I do like history sometimes but the workload is so so much and im not even passionate about it enough, one of the main topics i really hate. honestly if i had a time machine i would go back and choose different a levels but i dont, so im just wondering what my best way forward is.

Just to add some more context:
I got an 8 at maths gcse after being stuck on a grade 5 up until late march, unfortunately didn't do further maths and I do have a lot of spare time to catch up if needed (im quite up to date with biology and psychology)

Hi so im in year 12 currently doing biology psychology and history. Im hoping to go to oxbridge to do experimental psychology/pbs. My backup plan is neuroscience anywhere else. My a levels arent well suited for this as when i chose them i had no clue what i wanted to do so i just chose a broad range of subjects. However i only made this degree decision recently. My careers advisor said maths is well suited especially if im aiming for oxbridge as im competing with many people who wouldve chose maths, also some unis say u need two sciences and i only have one. My school is wavering towards not letting me switch history to maths but if they did let me, im wondering if this is worth it. I know its a hard task and im definetely not underestimating it, im predicted 3A* and got all 9s at GCSE so i wouldnt want to do anything that could risk these good grades, but good grades arent anything if i dont meet entry requirements. I do like history sometimes but the workload is so so much and im not even passionate about it enough, one of the main topics i really hate. honestly if i had a time machine i would go back and choose different a levels but i dont, so im just wondering what my best way forward is.
Just to add some more context:
I got an 8 at maths gcse after being stuck on a grade 5 up until late march, unfortunately didn't do further maths and I do have a lot of spare time to catch up if needed (im quite up to date with biology and psychology)

I'd at least try it out for a bit independently first but you probably won't have any problem at all catching up. Given your grades, A-Level maths shouldn't be difficult for you, and the AS-Level content covered so far is particularly easy and is largely just revisiting top end GCSE concepts.
You have 14 months until A-Levels, so you've only missed just about 20% of the time (less than that of the content), and most people don't even revise (much) in year 12 or the summer anyway. If you put in a few minutes extra a day you'll get there easily.