Hello,
I've posted before, and appreciated the advice given. Gave me some perspective and I've kept things as they were i.e. not getting involved with ex or his fiance and their life etc.
But, I wanted to share this as I guess I think it's a positive thing, for me and DD anyway.
DD was 7 yesterday. Ex was off work so we arranged for him to come out with DD and I for dinner and cinema as DD's birthday treat. He mentioned his fiance would also be coming. The arrangement was I was paying for dinner as ex pleading poverty as usual, and then paying for me & DD at cinema with ex & his g/f getting in with their monthly passes. Ex's g/f texted me offering to pay half of the meal which I said wasn't necessary as it was up to me & her dad to pay for that (he's supposed to be giving me the money later). She then said she would get ex to pay for DD at cinema as she felt it was a bit cheeky for ex not to 'put his hand in his pocket' 
. The dinner venue was changed for some reason, can't remember which, but ex's g/f got to the restaurant before me, DD & ex and had the table decorated with balloons, special table cover and other wee bits 'n' bobs. She also arranged for a cake told ex to buy one so DD would get cake/candle/singing to be brought out at the end of the meal.
The evening went brilliantly. DD absolutely loved it, ex actually contributed something he usually wriggles out of and ex's g/f really made a huge effort that added nicely to the whole thing.
Also, with reference to my earlier thread, I'm a little bit more reassured that the g/f isn't being 'hoodwinked' by the ex re money. She seems aware of some of his worst habits i.e. spending money he doesn't have, and doesn't seem to be blindly putting herself into a difficult situation. She's got a bit more sense than I gave her credit for 
And the advice I got previously helped me know when to just nod politely when there were efforts to drag me into a dispute, even though it was done 'light heartedly'.
So, overall, a nice pleasant evening which DD absolutely loved - said it was her best birthday ever .