Interesting, never realised RTCC had dropped from the official dealer list (see
https://www.morgan-motor.com/dealerships/ )...
I recommend the Peter Dron book on M3Ws.
https://www.amazon.co.uk/Morgan-Wheeler-back-future/dp/1845847636 Also not so sure about having an open top car under a cover ie not in a garage. I did keep my Caterham 7 for about a year under a cover but of course that had a hood. The tonneau under a cover should work OK but not sure the damp would do much good to the car... of course in the S of France or Florida it might be a different story! I would consider paying RTCC to garage it!