It’s all much easier if you have access to your subject teachers. Some will reply by email to you,nor be in school to help tomorrow, but in scope places, a subject specialist won’t be found in lots of institutions before Sept or next Thurs on GCSE results at the earliest.
It’s a bit late now, but lots of people will have requested scripts today whilst in school or college. Many came immediately and teachers will have given feedback this morning.
The other thing you need is to know the grade boundaries and the breakdown of marks between different papers.
Often, if you need a higher mark for a firm uni place, time is if the essence as they won’t guarantee your place for this year even with a regrade, after a few days. Or they might but not guarantee accommodation.
So I’d say, that ideally you’d want your application for a review in before this weekend.
If you are only a mark ir two off the next boundary and there’s a big drop to the next boundary, and if you know which paper was your weakest or where you already feels there’s a big discrepancy, then I’d go for it and not worry about marks dropping. Even if they do a bit, you are v v unlikely to drop to the next grade.
But you have to be realistic and honest. Did you work at the higher level consistently and this grad you’ve got seems b wrong…or is it wishful thinking.
I have to say that I have often seen marks remain the same, extremely rarely seen them drop (and only be a little bit) and pretty often seen them rise.
Personally, I’d go for it and not worry about the money.