Didimo,
Real pilots don't seem to have any problems with the charts as there are almost 500,000 movements a year on the ground most of which use the AIP product or Jeppeson Jeppview which are essentially the same! (but they are just black and white charts) I personally also have no problems with them but hey, everyone is different! Remember also that a lot of airline pilots use EFB equipment that displays these charts in the cockpit.
Parking at Heathrow is fairly straightforward.... Gate 1xx is terminal 1, Gate 2xx is terminal 2, Gate 3xx is terminal 3, Gate 4xx is terminal 4 and gate 5xx is terminal 5.... Gate 6xx are cargo ramps at the world cargo center. (shown on the Terminal 4 parking chart)
As a EuroHarmony Pilot you should request terminal 4 (long haul) or terminal 2 (short/medium haul) so you should only have to be concerned
with:
Aerodrome Chart - ICAO - For general overview of the airport.
Aircraft Ground Movement/ All Taxiways Chart - ICAO - For taxiway assignments and directions.
Aircraft Ground Movement/Parking/Docking - Terminal 2 Chart - ICAO - Terminal 2 parking chart
Aircraft Ground Movement/Parking/Docking - Terminal 4 Chart - ICAO - Terminal 4 parking chart
Of course, it always good to have parking charts for the entire airport and you will also need Runway holding charts and the other standard SID/STAR & ILS charts. You have to remember, Heathrow is the worlds busiest International airport, pilots don't just get to fly in and pick a spot, although many do on VATSIM and IVAO, it does take some practice to find your way around.
As for scenery, AEROSOFT Mega Airport Heathrow is currently the most up to date and the one that shows a completed T5 with all parking, Heathrow Pro from Gary Summons will not be updated and only shows a partially completed T5 and a trial download is available that places a large banner on the runways to try and get you to buy the final product. He is working on a New Heathrow Extreme product but I expect that is still a few months away. There is not really a decent freeware Heathrow scenery that is up to date.