Hi
There is a Gold rated COASSA caravan storage site just down the M62, the junction after the A1 going towards Hull, its about a mile from the junction, going towards Selby. Was silver rated, then got gold. We store ours there, its about a 20 minute drive for us from the north side of Wakefield. Its a good storage site.
Don't know about availability of spaces.
Hope this helps
Annette