I am prepared to be told IBU.
Trying to cut a long story short.
DP and I have separate finances at the moment.
I work PT and cover groceries and my car insurance (all I can afford). Everything else is down to him. We have 2 DCs and I do the majority of the childcare as DP has a much higher earning potential.
We are currently renovating our house (out of necessity) and have had to take out a substantial loan in order to get all the work done.
We have been making plans to visit my family abroad as we have recently had DC2 and my DGM is too ill to travel here and I know she can't wait to meet him. She's 86 and her health is rapidly getting worse. I've not been to visit for a year.
DP has recently said that due to the renovation costs he doesn't think we will be able to travel there this year. Around the same time I got some unexpected money from a family member and have told DP about it saying we can use it towards the flights. It's not much but can potentially cover the whole cost or at least the majority of the cost of the flights.
He has now said it would be good if I could use the money for one of the tradesmen we have working here, I pointed out that we didn't account for this cash injection and he countered saying we haven't accounted for the full cost of renovations 
He knows it's important for me to go this year.
He's has been trying to say it will cost us a lot of money for the full trip but I reminded him that when we are over there we don't really have any expenses unless we want to nip out for a bite to eat in town or buy a few bits (all optional extras) as my family provide accommodation and all meals etc.
AIBU to think he's being weird and unfair asking me to put this money towards renovations we would have had done regardless of receiving it?
P.s. We apparently can't afford to visit my family (mainly DGM who might not be around for much longer) but we can afford a 600-700 holiday he is wanting to plan for us in May.