I think you were thinking of Hendon, Joe.
RAF Museum website is at this link.
If you can get to the Cambridge area, Duxford might be of interest -
Website gives more details. If you click on the Visitor Information link, you'll find a transport information link as well.
You might also be interested in the
Imperial War Museum ...
Edit to add -
Oops! Beaten to it by REF. So, since you're using public transport,
here's the national rail enquires site