From the terminal it is only a small walk down Abelag (Biz/Vip) area. There is a few (lens sized) holes in the fence to put you camera though (usually not everything can photographed as there is this horrible double fence some places.
Other options is the carparks. The tallest one (don't remember the numbers) you can photograph take-offs and aircraft taxiing to take-off from cargo and Abelag. From the other one you can photograph some of what is parked in front of SN
Technic and the stands for smaller commuters. Landings can also be seen but not easily photographed.
The approach is also easily accessible but not by foot.
I was there for some hours on Feb. 9, movements are rather slow but with many goodies between, very often some EU-memberstates gvmt aircraft can be seen.
See here for further info.
Hope this helps, Michael
It takes courage to push things forward . . (Mo Mowlam)