I only have 3, Fred. Two grown up and one still at school (early teens!) but I chose my name to reflect how I feel about them.
To my knowledge it's fairly typical of dads to want to 'treat' their kids, while the mum does the 'bringing up'. (My wife is always telling me off for 'giving in' when she has set a rule... but that's for another site!)
We have never had much money either and found long country walks a good way to enjoy ourselves, but this may not be practical - unless the oldest one is able to help look after the others? (and the others young enough not to object!)
I see from 'Family Games' you've found some things to do with them. Have you found the link to this site -
http://www.dadcando.com/ - yet? (It's in my belated reply to King_t, if you need the full path.) Looks to be something for everyone there.
And why not have a word with the Ex. to see of you can sort out a on-to-one day?