She lives in a bit of a dream. She visited the local uni who apparently told them all not to worry about money because it will all be covered by loans and when I have mentioned that this isn't the case she tells me that the people at uni said it is
She has autism, and she hasn't been able to find a job, though good on her for trying. How realistic is it that she is going to cope with the transition to university and moving away from home at the same time?
Your DS might think about a degree apprenticeship, but I wouldn't advise that for your DD, and certainly not with a move away from home on top. Having said that, some apprenticeships are better structured than others. The ones I know about (in Scoltand not England, so maybe they work diferently) need a mature attitude and good time management, balancing work and study and life, and coping with two very different social environments (student and workplace) Look for a company with a big apprenticeship scheme and good support so she's not isolated or left to flounder.
Remortgaging (or releasing equity or whetever you want to call it) just so that she can go away is very risky. Your DD is fragile and her university career may not go to plan.
And it's not wrong for her to simply go to a local university; she can move into a hall or rented room later on as she finds her feet. The local university may even turn out to be her best option, with good support for students who have additoonal needs.
And it's OK for her to take life one step at a time.