Elixir,
I did the sim check recently without having stepped inside a B744 sim beforehand. It was quite unnerving, but I had done as much prep beforehand to make it less so. You can buy a detailed cockpit layout on the net (can't remember where - sorry). I also bought Flight Sim 2004 which has a B744 cockpit which is fairly representative, if you've never used speed tapes before to manually fly it will help.
Make sure you get familiar with AERAC plates beforehand as they are some what different to Jeppesen ones.
Make sure you're happy with procedural approaches as they feature quite a lot.
Make sure your RT is also up to speed, mine was a little gash and was commented on.
Most profiles seem to fly from LHR to STN with a div to BHX, then BHX to MAN or EMA.
Good Luck.