Just read this post and OMG, a lot of what has been said is true, but, you said you bought a top quality car cover......who ever sold that to you could sell sand to an Arab. £65 delivered is dirt cheap and as for fitting, I've seen less wrinkles in Nora Battys stockings!
I've been using a car cover for the last 5 years. The car is stored under a car port, but it has three solid sides, so a garage without a door. I only use the car about once a month, but before I put the cover on I always wash the car, dry her off, dust with a California dusted and a last quick detail.
My cover is made specific for my car ( tailor made ) and cost a lot more than £65.