Maternity leave with Twins

Faye • Twin mum and expecting my 3rd.
Hi! Can anyone advise me on what they are doing for maternity leave if expecting twins?? I've read a mixture of things and most seem to suggest finishing work at around 28-32 weeks? I've not been pregnant before so I can't even use my previous experience to help with my twin one! I'm just worried that I have a very demanding job, I'm a primary school teacher with a class of 35 five year olds. I find my job tiring on a normal non-pregnant day let alone when I get huge! Annoying I have to give 4 weeks notice but don't know how quickly I will grow and become uncomfortable, help!