Financial differences and inability to forward plan

[Pleaseaddcaffine]

So would this annoy anyone.
1 joint toddler dc and 3 step, away may half term for week in self catering cottage. Booked a lifetime ago, well over a year ago.
I've paid for the cottage in full. Dp just has to do spends and petrol for himself and his 3. I'm paying spends and petrol too as taking 2 cars so pretty ev3n split apart from inital costs which I paid.
He's zero money saved. Zero. Going to put it all on credit card as it will cost a fortune apparently. He does this every single time we go away and then moans whole time.
I keep reminding him beach, picnic, walking are free and fun but he won't have it as that's boring and insists on expensive activities or eating out/drinking out.
His living costs are low, 350 a month all bills apart from maintenance and car payments/fuel. No mortgage/rent costs as I own. I just am astounded that yet again he hasn't forward planned!

We did this about bills money etc and he agrees then never saves. Hence the end of my patience about it.
It would be 100 quid a month to clear holiday and kids birthdays - 1200 a year.

Kindletheforth... Thanks though that's extremaly sensible advice. I wouldn't want to exclude the kids but ultimately I guess if it's me and ds then that will have to do. Bit sad though

He always had money to indulge his hobby though doesn't he?