I would agree with Thom@s, the best results are probably at either end of the runway, for approach shots. When I go to NCL that's where I spend the majority of my time.
Rather than me explaining how to get to these points, click on the link below for detailed directions.
(If you're interested in NCL and you get a chance, have a look around the site as a whole as I'm sure you'll find it interesting - it's a really good, informative site with regular updates.)
Hope this helps you, and as a newcomer, hope you're enjoying airliners.net.
(P.S. I'm sure NCL is better than Bristol !!!!