I'd keep ttc and see what happens because it's possible it will take another 4 months anyway (although I hope not for your sake!)

I didn't worry about paid maternity leave because there were too many restrictions on it at my work - ie if you leave within 12 months of returning, you have to pay it back, you have to work a minimum of 3 days when returning, I only wanted to do 2, you only get half when you go on leave, half when you come back (how ridiculous is that?? why would you need it once you were back at work??) etc etc.

You'll get by without it, we all manage somehow!

Good luck!