"in the end i thought it better for him to go then rather than resent me for making him stay"
This is exactly what I said when my husband wanted his freedom and went to work in Hong Kong. He came back after six months because he missed us so much but told me on the night he returned that he didn't want to be here and he returned to HK two weeks later and that was the end of our marriage. We probably would have split up anyway as he just didn't want to be married with a family. HOWEVER, I should have stood up for myself and my girls and said 'No, stay and face your responsibilities' but I didn't want to be a nag so I let him go.
Also, you say that when you decided that moving there before the birth wasn't an option he booked a flight home. Which begs the question - when was his original return date if it wasn't before next week? Was he coming home before the due date?
I understand completely why you feel so defensive and adamant that everything is going to be ok (I've been in similar relationships myself although without the emigration bit) but, going purely from what you've written here, it would be wise to stay here for at least a couple of years until you take the huge step of emigrating.
One final thing, it's never good to use one person for all your support. It's a lot of responsibility for the other person and not good for you. I know what it's like to be alone and pregnant but you need to be confident that you can do it alone if needs be which you've already proved once.
You sound like a really lovely person but don't be afraid to stand up for yourself. From what you've written here he hasn't behaved terribly well up til now and you've gone along with it to keep him happy. Why did he need to go home and bum around for five months? Hasn't he been bumming around in this country for quite a while already (I know he's been working too)? Couldn't he just go home for a month? Surely he could have deferred his Uni place from here?
I'd also look a lot more closely at what your position would be if you emigrated and the relationship ended. You say you're sure you wouldn't be separated from your child but others are saying it's possible.
His words might sound committed but his actions are showing the opposite from what I can see.