Accrued annual leave help?

Hello.

I’m due back in October from my 2nd mat leave. Prior to going on maternity leave I used all of my annual leave hours to give me an extra month off before I started mat leave. They reset in April 2026. My manager has just informed me I need to use all of my accrued leave before I return in October but I don’t think that’s right as it won’t leave me with any leave the between my return and April? He also said it’s based on what I was working before maternity leave (30 hours) and not what I’m going to be working (28.5). Can someone advise please? I work for the NHS!