When to take maternity leave?

I need to let head office know but I’m not sure! I’m 25+5 today and they sent me an application to fill out which states when i take maternity leave so they can sort out statutory maternity pay. I’m saving my holidays in work so I can add them to the start of maternity leave, finish earlier and use them up since I don’t know if I’m going back to work 100%.

My due date is June 3rd.

Is starting maternity leave/pay June 1st too late? It would mess my holiday pay up and maternity if she comes earlier and would mean I would finish work May 4th.

I have the option of starting maternity on 25th May? This would give an extra week incase she is born at 39 weeks and I would finish work April 27th. Obviously she could come at any time, but I’m trying to work this out realistically lol

It’s so confusing trying to work my holidays and maternity out and join them together🙃