The A300's do operate a number scheduled services to popular destinations likes ALC
You will need to spend a bit of time looking through Monarch's reservation system on the website and pretend your making a booking, where you can go through to the screen and choose where you want to sit and from here you will be able to tell the aircraft type.
Nearly all the A300 routes are from LGW
, where they are based...
For the last few years Monarch has been operating an A300 on Saturday's from LTN
during the summer months, which is a W route with a Manchester based aircraft. I just took the opportunity to see if this route is operating next year and it is... Flight number ZB870 and ZB871...
I would however be careful booking anything too far in advanced, as equipment changes could easily happen!