The museum is situated on the site of the old doncaster airport, If you find "The Dome" liesure centre, off Bawtry road, the oposite side to the racecourse. The turn off is at a mini roundabout, near Doncaster Rovers FC, Follow the road, passing Tesco's, I think (don't do shopping), on the right, at another mini roundabout (within 50m of the first). Carry on up the road until you reach the next roundabout, look for signs and follow. It's actually been some time since I last went, so it might actually be at the next roundabout? Anyway, if you get as far as Yorkshire outlet, you've gone to far. The sign isn't very obvious and is, or was, when I last went, a propeller. The sign sends you down what you might think is a disused road, have faith :-)
Hope you can make it. If you can let me know and I will try and do a recce on the location and give you better directions
Mal