I agree with Bob, I have used the Beechwood Grange site a number of times, partly becaue the Rowantree one was always full. It is a pleasant site and being close to the Ring Road, does not have the hassles of narrow approach roads that the Rowantree one eveidently does, at least according to the CC. There is also a Park and Ride half a mile away although as I do not have a Bus pass...yet, I cannot confirm whether or not that would be an advantage for that reason..
However, while I sympathise with Jo-anne for not being able to visit Rowantree when she wishes, possibly she can look at all the alternatives, and not be too downhearted.
Firstly, if Rowantree is so fully booked, then she will not have to live 'cheek by jowell' with a crowd. It is unlikely that every weekend there will be totally new people staying, so I suspect a large number book it regularly and probably meet similarly minded people. At least she will miss having other van occupants glaring at her for daring to use one of 'their pitches', and will be able to chat with other vanners, without possibly feeling she is encroaching on a private Club.
I agree with Bob and suggest she try the Beechwood Grange site. It is also far more convenient for seeing the Yorkshire Moors, which in my opinion, are far more interesting than grubby York. Pickering is just up the road, a lovely market town and of course is the terminus for the North York Moors Railway, which young and old thoroughly enjoy. The Station Hotel in Grosmont does excellent fish and chips, which is something the dirty and overpriced pubs in York have yet to learn.
So, look on the bright side. Jo-anne may not be able to stay in Rowantree but there are better alternatives available.