There's been a few bits of news on Table Top Gaming news about a new show coming the South West this year for grand scale gaming.
Called "SMS" and run by Angel Barracks it appears to be catering primarily to 6mm at the moment, but in their spiel they talk about 10mm and sub-3mm, however as yet there are no traders or games confirmed for these scales. Also so far it all appears to be Ancients and Napoleonics with one Alt-WW2 demo-game.
It's being held over in Bristol on August 14th and if they can get a few more traders and interesting looking games I may well give it a look. I'll keep an eye on their pages and add an update if it looks like really taking off.