Im my opinion I think you should choose the most suitable airport lo land in Italy with reference to your flights schedule and then focus on the transfer options.
I don't see any major disadvantage in the airports you can choose arriving from London: MXP, LIN, BGY, VBS or VRN. All of these have easy link with the highways and also frequent connections to the train station (in MXP the train station is in the airport and you can reach Como in one hour, just take the Malpensa Express to Saronno and then change for Como lake station).
You forgot to report an important detail: are you going to Como city or in another place on Como Lake? Usually for weddings people choose some nice villas or locations on the lake that are far away from Como and you have to consider this. If you are going to Como you may choose the car rental or the train, but if are going to the Lake region the only option is the car.
With reference to your proposed temptative schedule I would choose by far lo land in VRN instead than a transfer from LGW to LHR.