I like my 80-200 f/4 very much.
A 50/1.4 is relatively inexpensive, and I might get a 35 or a 24 for wider shots.

For a bit more, you can get the well respected 35-70 f/2.8 (KEH has them for around $400, but I realise you are in the UK). It's my walk-around lens.

This page http://www.naturfotograf.com/lens_surv.html has some evaluations of Nikon lenses...