Mat leave has to start the day your baby is born , so if you're on annual leave and have the baby it would start that day, I'm not sure what happens to the rest of the leave !
With both of my previous pregnancies I finished up about 36.5 weeks, 2 weeks annual leave then mat leave started . With my second I planned to work later but honestly I was so fed up by the end, and ended up asking to go off early. I think it depends how physical your job is too . My second was overdue and people said I'd be bored but I wasn't at all. I couldn't focus on anything at work either, my head was in the clouds .
Eeek @Giraffe888 I know ! 2 sleeps! My wee girl already knows and she's dying to tell her friends at school so she's been counting down the sleeps too lol, bless her she's actually managed to keep it a secret