Hi all
After you all provided such excellent support on this, I thought I'd come back with an update. I suspect it might not be the last...
(It's partly so that I have a written record of it too.)
As I said, my daughter went to her dad's on Saturday night and came home yesterday. She and I have made great strides in sorting out her room and clearing stuff she no longer wants, which is great! And we've had a lot of fun doing it - finding long forgotten stuff, reminiscing about her childhood and talking about the great adventure that lies ahead.
We've just stopped for a break and she told me what happened on Saturday.
So she told her dad that my partner and I would also be going up because she wanted us there too.
He wasn't happy 😄
He first of all said that he and his wife had been looking forward to taking her and getting her settled into her new room and spending the day with her. That they have bought some essentials for her and it was 'ungrateful' of her to want me there too 
So she said that I had also bought her stuff and so that was irrelevant and she wanted her mum there to do all of this stuff with too. They've effectively tried to buy her loyalty.
Then he asked if she really wanted the first time we met each other's partners to be when we all dropped her off at university together?
Then she said that, as he didn't really talk to me anyway, it was always going to be a big life event the first time we all spent any time together and she couldn't see why it was a big deal anyway.
Then he said there would be too many people and that it was really only a quick drop off; the parking might be limited (fair point) and they wouldn't be hanging around (most of which contradicted his first point somewhat).
She said she couldn't see why that would be a problem. It would get the job done faster. she also said that it wasn't her fault her parents had divorced and reiterated that she wanted me there so, if parking was going to be an issue, she was sure I'd be happy to ltravel in the car with him. (Apparently he "got pissy" at that). And his wife said that wouldn't be appropriate. She said I wouldn't mind so that was their choice.
Then he said that they had planned to book a hotel room and stay overnight just in case she was upset the first evening and needed him. And so, if I was going too, they'd have to sack off that idea.
She wasn't sure why this was but said she'd be settling into her new place and not want to see him anyway. She also couldn't see why they couldn't stay overnight anywhere just because I was going to spend the day in the same place 🤷🏻♀️
He didn't like that either.
Then she said he acted really hurt and said that maybe he shouldn't be going at all and said that maybe they'd just go up for a weekend in a few weeks. She told him that, if he didn't feel comfortable going up with me and my partner there too, maybe that was for the best.
She wasn't supposed to say that 😉
He said that he thought I should be the one going up a couple of weeks later and she pointed out that I wouldn't be able to realistically go for a weekend until the end of October so it would be easier for him if he felt that was for the best.
She completely understands that his responses were all designed to emotionally manipulate her and she's really pissed off about it. She doesn't feel guilty and her position is that, if he can't be a grown up about it...
Apparently, they "need time to think about it". She's waiting for the financial manipulation to come out now becauae none of his 'nice' tactics worked (nice because it was all framed as supporting her, helping her and spending time with her).
She did then say that it makes more sense for me and my partner to be there. She lives with me and he does loads for her so she feels like, if anyone 'deserves' to take her, it should be us anyway. And it would be weird if I wasn't there. She knows her dad is just grand gesturing and 'glory hunting'.
She said that she doesn't really see her dad that much anyway.
I asked her what the upshot was then, are they coming or not? (In case I'd missed something in the retelling). She said she didn't know and that he's thrown his toys out of the pram so she's just going to wait for him to pick them up again.
I reiterated that I didn't see why we couldn't all go together and I was still happy to drive just her and her dad if that's what she wanted and he thought the parking would be an issue. She said she knew but his wife clearly wasn't happy with me going at all and wouldn't have stood for that so she didn't mention it.
Why his wife thinks she's got any say in the matter anyway, I don't know!
So that's where we are. She is completely aware that, if he doesn't come, it's his choice and not because shes done anything wrong. That she has angered him by not doing as she was told and not falling for any of his emotional bs. She is bemused by the fact he thinks wanting me there makes her ungrateful because he and his wife have bought her a few essentials.
We had a very brief chat about how, now she is 18, she is an adult and she can make decisions for herself that are based upon what she wants and her best interests and not because she is trying to 'please' anyone else. She gets that.
And I've given her Why Does He Do That? to dip into as she wishes.