Stag do while coming towards the end of Phase 2

Alright everyone,

I’m starting RAF basic training at Halton in November and I’ve found myself in a bit of a predicament.
I’m best man for one of my mates, so I’ve got to sort his stag do. It’ll most likely be sometime in May, which should hopefully be around the end of Phase 2 or not too far off, depending on how everything goes.

Obviously I know training comes first and I’m not expecting the RAF to move things around for me because I’ve got a stag do. I’m just wondering how much flexibility there is towards the end of Phase 2 when it comes to leave/weekends.

Would you guys recommend I just wait until I know my Phase 2 completion date before booking anything, or is there usually enough leeway to request a weekend off if you give plenty of notice?

I’m basically trying to avoid booking something for 20 lads and then finding out I’m stuck on camp that weekend
Anyone been in a similar situation or know what the crack is with leave towards the end of Phase 2?
Cheers!