I meant to reply to you the other day but it slipped my memory!
Prestwick is pretty good and accesible both by train and car. There is a banking alongside the main runway at the west end next to the tower that you could walk to in about 10 or 15 mins from the railway station or you can drive your car right up onto it and view in comfort! Landings are mostly from the west but you can get good rotations if they're going out the other way.
Shots like these are available from this location. Taxiing out and landing/departing towards the east.
And departing the opposite way...
There is also a bridge over the railway line that allows a view of approaches from the east but I prefer the banking much more.
GLASGOW is pretty easy too (with a car). The perimeter fence at the east end allows reasonable view but only through a fence (there are a couple of wee holes that you can use). DO
NOT park your car (if you're driving) near the crash gate as the police will get most upset with you!
These shots were taken from the crash gate
There is also "the mound" at the west end of the runway which is accesible via a playing field round past the Loganair hangar. Take some boots with you as it's quite muddy.
These are from the mound...
Hope this helps!