What's the insurance for? £170 a month sounds like loads, that's nearly £2k a year. Our total insurance bill (car, motorhome, buidlings and contents) is less than £600.
And if your DH gets £120 a day after his dad has put some aside for his tax, his true rate of pay will be much higher, around £150pd. Is he on the CIS scheme, like a subcontractor? If he's not, it sounds very much like he's an employee to me. I'd be very wary, HMRC are really clamping down on spurious self-employment.
I think you need to sit down with him and have a serious chat about money and who pays what. You seem to be meeting the lion's share of everyday costs (food, nursery, kids' clothes, insurance) out your £1,140 a month, while he just pays for a couple of utility bills (although someone must be paying council tax, which you haven't mentioned).
I bet if you worked out all your family outgoings, he'd be paying a much smaller proportion than you, despite having a much larger income. That's really not fair.
Hard to comment on whether or not he's tight, as he's obviously committed to saving for a deposit, but if it means you're walking round in maternity clothes while he's madly squirreling money away, that's really not on.
My DP is tight, which is why we have a joint account we contribute equally to and the rest of our money is our own!