Karenanne, I fail to see why a man who thinks that playing footie and golf is more important than living with his children should want to spend Christmas and birthdays with them. Surely he could play golf and football on those days?
TBH, I don't see how it could possibly work. It sounds to me like he wants to have his cake and eat it - have all the nice, fun stuff with his kids - Christmas, birthdays, nice outings - without any of the crap stuff - endless bickering, getting them to bed on time, getting up five times in the night when they're ill, not having sexual access to other women because he's a father.... in short, he wants to present the facade of a caring father to the admiring world, without actually doing any of the caring.
In time, that might start to gall you. Call me twisted and bitter, but it certainly would me.
There is also the other issue - if you seem so close to your ex, no other honest man will touch you with a barge pole, because they won't be sure if you are really free. Lots of creeps will have no scruples, which is fine if you don't mind dallying with lots of creeps, but not so good if you've set your sights any higher.
I think you need to have as businesslike and civilised a relationship with an ex as it is possible to have. If he is actually as socially and emotionally functional as to want to maintain a proper relationship with his children, then firstly, two big cheers to him, and secondly, you need to make sure it is on terms acceptable to both of you; ie: you present a united front to them, you don't undermine each other's disciplinary code, they understand that they can't play you off against each other. But the family days out send out false messages to the outside world and to the children themselves. Don't forget that most children of separate parents spend their whole childhood believing and hoping that their parents will get back together. It's a act of cruelty to encourage that hope, unless both of you at the back of your minds have a secret belief that it might just be a possibility... is it?