Three more pages since I last posted here and it is obvious OP has a chip on her shoulder and has been drip feeding. It is becoming clear that this is all about resentment for not winning custody in the first place and resentment for having to pay even £100.
Firstly, he doesn't have joint custody. He has his child week-ends and holidays and I don't believe for a second that this is ALL of it. Funny how suddenly, there are 5 days that she isn't there during the school holiday. I expect the same applies to Xmas and probably Easter. He was paying £100 which is low and reflects on how often he had her.
I also find it amazing that OP and her OH had a job that offered more than 6 weeks holidays.
Lost all credibility with the post saying that the ex could afford holidays and therefore she'd be fine. Says it all really. It's one thing finding yourself in a bad position (won't even go as to the reasons for the dismissal) that impacts on an entire family and having to make the best of the situation, but most people in this situation would actually say that they are sorry that they won't be able to rise to their obligations for awhile but they intend to do anything to be able to get a bit of money to help, maybe asking if there is anything coming up with school towards the end of the year, a trip, a show, something that will involve some costs, and say that he will see if he can try to help.
As suggested by a number of posters, a decent father would take any extra work in the evenings (no, the SD is not there evenings M to F) to help, even if it meant he could give his DD only £25.
As for contact, nothing mentioned about the cost of travelling. Since he doesn't have anything at all, does this mean that he won't be able to do any of it? Did he tell mum that she would have to do it all? That would explain the stopping contact comment.
This thread should have required only one response 'no you don't have to pay anything for your SD whilst your OH is out of work', but the rest of it just shows that there is a lot more to it than that.