There's also this free flight sim for Windows, specifically designed for IMC training:
http://66.249.93.104/search?q=cache:...en&lr=&strip=1 It used to be a commercial product but the authors then released it for free.
It has some annoying features but I find it very good for practising interpreting navaids and flying procedural approaches.
It won't have Robin Hood Finningly Doncaster Sheffield Intergalactic Spaceport in its database but you can easily add it.
Unfortunately, the actual web site has disappeared (hence the google cache result above). The licence does allow it to be freely distributed though so if you want a copy, PM me.
Mark