£88 an hour sounds a bit steep for a 172 sim, but if it's loggable, I guess it all counts. The key thing about the sim is the number of different things you can cover off in that hour, so it probably equates to 2 - 3 hours in the actual aircraft (no time for taxi t/o, you can reset at any point, etc.)
Certainly a good idea if you can't get into the sky to practice that way - I even used Microsoft Flight Sim to practice holds for my IMC rating, and it's amazing how even a basic sim can make some difference.
Good luck for Saturday - hope it goes smoothly for you, and keep that altitiude in the turn!
DW
