No contact for 8 weeks - last trimester

I have two children 6&8 from previous marriage & I'm currently 35weeks pregnant. The babies father has been inconsistent through out, not made any effort to help me, only attended one scan & has been up & down with communication. He seems to follow a pattern, where he can be present for three weeks & then goes downhill. We have never lived together & the baby wasn't planned but we decided together we wanted to keep it.
I wanted him to build up & have a good relationship with my children before the baby was born but he hasn't tried at all. He always says he is too busy, but I know we're just not the priority to him. At 27 weeks pregnant I got really upset & said I couldn't cope with how he was anymore & my children need to feel comfy with him too & he needs to make more of an effort. I just mean a friendship, I don't expect step dad of the year they have a great dad off their own! Anyway I haven't heard from him, since.. this was 8 weeks ago.
It's been awfully emotionally but had to keep it together for the children & still working full time. He told me he would financially support me through maternity leave etc but I am so worried as looks like that won't happen & i genuinely don't know how I am going to make ends meet. I have written to him three times asking what he wants to do financially & access wise but nothing! Any advice welcome :-)