The WW2 weekend is a massive event that takes place over three days starting on the Friday. The main display is at Quorn, just a short walk from the VAME Meet, with US military hardware, tanks, guns etc. There are stalls where you can buy genuine WW2 guns and stuff if that floats your boat, a beer tent with WW2 era music, etc. I always enjoy the vintage aircraft flypast, although the best is usually reserved for the Sunday (normally a Spitfire flying around the station and alongside the steam trains). There are several reenactments during the day at different stations.
I posted a few photos of the WW2 event from a previous year here:
A full family ticket usually costs something like £35 to £40, which isn't cheap, but it does give you unlimited rides on the steam trains all day and access to all the displays and events throughout the day.