Maternity leave and benefit

Escapees

Just wondering how early maternity leave can be taken as probably won't be going back to work afterwards? Citizens Information says that you can take a maximum of 16 weeks before the due date, meaning you can go on leave as early as week 24.

But they also say that you have to apply for it 6 weeks in advance, and include a medical certificate obtained at 24 weeks. So that means the earliest you could go on leave is week 30 (24 + 6 weeks)! ???

Also, if employer does not offer a top up on the maternity benefit, is it just simpler to resign beforehand if not intending to return again? I've read alright that there might be an entitlement to paid holidays accrued over the maternity leave, but this wouldn't amount to much as job is only part-time and min wage anyway.