Hey bud! I might be able to help u out. I'm doing Economics, Politics, Maths, Further Maths and EPQ. I am planning to read Economics this year so Further Maths was KINDA a compulsory for me. It is tough and time consuming but my advice is that start researching your EPQ topic as soon as you can. With the whole pandemic thing going, try to research your topic of interest. I finished writing my EPQ back in Year 12.
For a Maths degree, I think you need to sit for STEP papers but then again, if you can't do Further Maths, I can't imagine if you can sit for STEP papers that easily. I finished Further Maths and attempted few STEP questions and it was still hell. Further Maths might sound tough and all but I think you should give it a go. Drop it in Year 13 if u can't cope.
Surely, Further Maths is a strong added value to your university application in my opinion.