I think that when people start by questioning whether they should do FM,it’s not a good sign. FM should be taken and expected to be taken, unless there’s an extremely good reason not to - ie your school or college doesn’t offer it.
If FM looks daunting or unappealing, the student probably isn’t right for an Econ degree at the most competitive places. The majority will have it. You really do t want to place yourself in the minority if you can avoid it. It just gives yourself more of an uphill struggle.
Rememebr, most applicants who get offers will have extremely high predicted grades and do really well in admissions teats, which willbe mathematical. You have to be looking to maximise, not scrape the minimum stated requirement. Most will have far in excess of it. Okay, every year there will be people who get offers who do t have FM. There will be people who do t have the very top GCSEs or top A Level predictions, but they will be a tiny number out of everyone. Unless you’re got strong mitigating circumstances which can explain why your GCSEs aren’t stellar or why you don’t do FM or don’t have top A Level predictions, you probably just aren’t a strong enough candidate.
If you do have mitigating circumstances for these things and are super-duper and likely to do really well in the admissions test, it’s worth having a go. You might be in the small number who do t fit the general mould, and they want those people to apply. But really they aren’t interested in people who are are a bit mediocre without mitigating circumstances. Good but not exceptional GCSEs, scraping the standard offer in predictions and not having really extended themselves with wider engagement just doesn’t cut the mustard, when there will be far too many candidates that achieve highly in all these categories and still can’t offers. It’s not for candidates who are solid and decent, but fancy a bash at it, or whose middle class parents are aspirational and think their kid with 7s at GCSE is very bright.