I take Physics (Edexcel), and Further Maths (OCR MEI), and I’m going to study Physics and Maths at uni.
If you’re good at remembering lots of information, I’d recommend physics over further maths. There is a lot of applied maths in physics, but it’s about 40:60 maths : words. For example, the third paper (at least for Edexcel) is practical heavy with no multiple choice questions, and every paper has 2 wordy six markers, and it isn’t always clear what the six marking points are.
Further maths is definitely easier to study/prepare for, and is very interesting (after finding out I’d received an A for the AS, I actually quit Chemistry, so that I could continue with it), so I’d encourage you to give it a go. I got a 7 at GCSE and I’m predicted an A, so as long as you put in the effort, and ask for help before topics become a problem, the content shouldn’t be as intimidating as it first looks.
What’s really good about taking Physics, Maths, AND Further Maths is that all the courses overlap, ESPECIALLY for mechanics. I’d encourage you to take all four options for a bit (if that’s possible), and then drop whichever one isn’t working for you.