Had some more news from my dealer today. Last weeks new list had me at a June build if I remove the towbar and a month tbc in the second half of the year if I didn't. Kept the tow bar and today received a confirmed build date of May 17th! So in my case the list looks to be out of date within a week.
I have been told that the build could take a long time and we are very unlikely to see it for July so probably doesn't help us for this summer due to fixed holidays. But from what I understand they build the vehicle up to a point and then it will sit waiting on a towbar presumably with a lot of others waiting on the same. Sounds like a strange approach to me when they could presumably move down the list and build ones they can actually complete!
Thanks to all who have been posting their experiences which at the very least have helped us realise we're not in the minority. Happy that its progressing at last though