There is a spectators viewing area located between terminals 1 & 2. It is sign-posted, but it can be a bit tricky to locate.
There is a shop and a cafe, and a viewing gallery in the open, which can be quite full with photographers. There are a set of departure screens in the lower gallery - which is out of the wind and rain.
It is normally opened during the hours of daylight in the winter. I believe it is closed early evening in the summer. I'm not sure of the opening times, but its certainly open after 10 am.