Depending on on distance and duration of trip……
Driver to and from the airport. I have an excellent driver who picks me up at home, and collects me from the airport. No need to worry about driving tired, no need to faff around with parking to terminal transfers, I get dropped at the right part of the terminal. Yes, it’s more expensive than driving yourself (mine isn’t cheap, BMW 7 series at all hours) but when you factor in the hassle factor of driving/parking it makes good sense.
Worth the ringing around some of your local drivers, I’d say. Look for business travel types, as they’re more likely to be to and from LHR regularly, keeping costs down. My driver sometimes has five or six trips a day to/from Hampshire to Heathrow.