The 'M&G' reception centres at T1 and T3 are well signposted – so it'd be much easier in my view to find these than to faff about looking for remote car parks.
However, they're not Meet and Greet in the 'traditional' or literal sense: At the M&G barrier you are instructed in which row to leave your car. You then drop off your car key at the reception centre and walk to the terminal. On collection you are handed back your car key at the reception centre and have to walk to your car. At T1 it could be up to 200m away. Staff at both T1 and T3 are generally very courteous. I use them about twice a month.