York has a good motorhome friendly P&R system. A19 road McArthur Glenn Designer outlet is accessible from the South, just drive in and find a sensible parking place. Rawcliffe Bar P&R on the A19 North side is even better. Drive up to the barrier and the attendant will open it for you, but no overnight parking.
There are several certificated sites around York, some on or near bus routes.
I am going to York again in a couple of weeks and have booked a CL from the C&CC Big book, ref York 105 185 which is in Earswick on the Strensall bus route.
Loveley city, but don't take a MH in unless you are a masochist, or going to Rowntree Park CC site; but if you are then follow the instructions closely. Nice site, but a bit pricey in summer and a swine to book any time of the year!