I don't necessarily think a relationship where you 'tell' or 'allow' your partner to do what they want can work in the long run. It can build up resentment between both parties; you have to display the fact that you trust them to make considerate choices as part of a couple (or family).
It sounds like you have come to a mutual understanding about your financial situation and the implications that this trip may have on it. With that awareness, your OH surely can decide for himself what is important to him and if there are any compromises to make.
Hope you can come to an amicable agreement; there'll be plenty more of these situations coming up in the years ahead with a child in tow, so its all good practice!
It sounds like you have come to a mutual understanding about your financial situation and the implications that this trip may have on it. With that awareness, your OH surely can decide for himself what is important to him and if there are any compromises to make.
Hope you can come to an amicable agreement; there'll be plenty more of these situations coming up in the years ahead with a child in tow, so its all good practice!