Yeah, MY21 is definitely back into consideration, as I can see long delays coming in for all brands. I don't want to be keeping my current car past the end of August as the MOT & servicing dates will be getting much closer (October).
The heater may actually be a non-issue for us, as it is likely to be plugged in overnight anyway, so if it the pre-conditioning is needed it shouldn't adversely affect the battery range.
Typically I sent an email to the dealer yesterday to say we're not going to take the MY21 any further. Time to give him a call and eat some humble pie, he must think I'm a right idiot!