Thank you jebk, NewbieRunner, Up In the Air and MAN Pax Your insight and help has been really useful.
I always tend to use the MSE links to book airport parking, as you suggest - saves a lot
The Meet and Greet that I have is not the official meet and greet of the airport, but is a third-party one. Apparently, I have to phone them when 15 minutes away and then "Drive to Terminal 3, and park in set-down area... and [a member of the team] will be ready to meet [me] at the kerbside."
Hopefully that will go okay next Friday (the 23rd November). I'm leaving Lancaster at about 3.30pm/4pm to get on the 7.25pm BA1407 down to MAN before heading onwards to the States. Usually, I wouldn't have any concerns but I rarely fly from MAN, I'm not familiar with the Lancaster area, and I think it is the first night of the school half-term. Hopefully I have allowed enough buffer time to get to T3 and this third-party meet and greet will help.
Thank you all so much again, and have a great afternoon
Simon.