This whole exercise should be to keep the welfare of the children at it's centre. OP is sending clean clothes, sun cream, hats etc. Children home to her on Sunday to "come down" from their first weekend with their Dad at his new house, new beds, new routines etc. I can't imagine how young children would cope with all these big changes and expect normalcy going into school on Monday morning straight from Dads.
OP is quite rightly looking at / after the children rather than trying to score points against the ExH. It's not about making his life easier, it's about keeping the children the focus.
ExH has a couple of weeks before school holidays to get his act together. OP has her solicitor contacting her re the 50/50 this week.
OP, any kick-back from ExH maybe remind him, this is what single life is when you have children. It's no longer your job to sort stuff for him.
Also, I'd suggest checking your Credit Report and getting him off anything, joint bank cards, credit cards, anything that links you. This "skint" comment doesn't bode well and you don't want to be tied to any financial decisions he makes! Experian etc.