Nikon Fit 100-400 Telephoto Zoom (or similar)

[Skyman]

Grateful for some advice please. I want a long lens to supplement my current 18-105mm which is fitted to a D90. The lens needs to be suitable for wildlife amd motorsport. Budget is upto £700 ish. Thanks in advance.

[Skyman]

If I was to stretch to Nikon 70-200 VR 2.8, with a teleconverter, would this be OK to handhold or is a tripod a must given its weight?