"DH is done with parenting now he says they need to stop needing us and I should not be spending time listening to them rabbit on and on."
Umm no. Listening to your children is not "parenting" it's having a relationship with them and that should continue into adulthood! You don't stop having a relationship with your children when they become teenagers!
"I went shopping with DS this afternoon as I needed some bits for college "
Perfectly normal and healthy thing to do with your teen.
"If they go out and I am out or at work DH will not take them or pick them up from anywhere - he makes them walk or get an uber. One is autistic and one suffers from anxiety so they don't feel safe in ubers or walking and I will always give in and take or pick them up. "
Neither approach here is fine. If they are anxious then you need to to be working with them to become more independent. Ideally this would have happened way before now but you are where you are. Your DH just chucking them in at the deep end or you just giving in and doing it for them, is not helpful at all. You need to be building their confidence so they can get themselves about without feeling anxious.
"he wants to go away for a week in October but I don't feel the kids would cope without me here."
At 18 and 16 they should be able to cope with this. If they can't, you need to find a way to work towards them being able to cope as this is not healthy. Your teens should be working towards independence from you (which is why most tend to gravitate towards a friends and spending time other than with their family). The fact yours aren't is an indication that all is not right with their development. Which is what I think your husband is recognising but not expressing in a helpful way.
It's not ok that your children of 16/18 are too anxious to get about by themselves or cannot cope without your presence for a few days.