Not sure if this is in the right place,annual leave vs sick leave

[Rumpleteaser]

I would say you do need to get a cert if that is what your work is requesting as you are effectivley converting your annual leave to sick leave.

[HotI]

annual leave often requires prior notice. so quite possibly a sick certificate is needed if you taking annual leave with minimal notice.

check with your union if you are not happy with it. can you do stat dec s instead of medical certificate?