Sixth form reserve offer

Ok so I've just gotten an email from my priority sixth form saying they weren't able to give me a conditional offer due to lots of applications for my subject choices (fm maths phys cs). Anyways, they said they were still able to offer me a reserve offer, and if I email them with my grades on results day they may be able to give me a place if some people don't take up their offer.
I just had a few questions to ask in case anyone here knows:
1. What are we looking at in terms of chances? Its a fairly prestigious sixth form but I'd assume some people may not take up their offer allowing me to swoop in.
2. About how many people would they give reserve offers to? For context, school has around 70 places with like 1200 applications. Not looking for an exact number but like ballpark estimates. (e.g like 20 or 50 or 100+)
3. Would I be better off just emailing them to ask these?

I’m guessing you’re talking about St Marylebone? If so, I got the same offer. Honestly I don’t know but right now I’m considering just going to a different school that I’ve gotten a conditional offer from. I think my grades are excellent and I want to go somewhere that actually appreciates my efforts and grades. I’d try to be as quick as possible on results day to ask if there’s a spot available for you! I’ll probably be doing the same depending on advice from my teachers and stuff like that!
There is no harm in asking them for a rough estimate because they’ll probs have the same patterns and questions every year.
Hope this helps

haha yeah i am!
personally my predicteds right now are alright and better than what I applied with but i'm sort of desparate to get in to the school as i got a rejection from my 2nd choice and 2 acceptances for 2 schools which I would rather not go to.
so i wouldn't mind sacrificing my dignity and trying my hardest to get into stm.
thanks for the advice! good luck with your sixth form, wherever you go
p.s what grades did you apply with? i applied with 9999987777 and i thought i had a good chance of a conditional but whatever