Tough one Anna and I sympathise on the extortionate crèche prices. We are being bled dry here with two, even with dd1's 15 free hours
, because of the same kind of inflexibility.
I'm definitely a big fan of childminders when they are little, I like the sense of family routine and the quieter pace. Nursery can seem quite manic in comparison.
HOWEVER. I would imagine that you and your DH have looked at all the options and sometimes it really is a case of going with the option that will be most helpful to your sanity and/or most straightforward, even if that's the spendy option. You are in a position where you don't really have family support, you're pregnant and your work isn't full-time fixed hours (do I have that right?) so if the crèche is 5minutes from your house that's a big plus. There may be times ahead where you or dh might need to work more hours or when you're getting very big and exhausted and having that kind of flexibility (ie sending in ds whenever you want for however long you want) can be a great help.
So, long story short, go with whatever you feel will suit you best right now and remember that no childcare arrangement has to be forever. It's just what works for a particular time in your life. You don't have to justify the price or the decision to anyone.
I am hoping that we'll really notice the extra money once both of ours are at school but somehow I doubt it!