Don't hold your breath.
They could hold onto the land for years before they start building...when house prices have gone up. They are likely to clear the derelict stuff as the site is deemed safer, so if anyone tresspases they are less likely to get injured, etc, and the site is worth more if cleared and planning permission granted...but it could easily be 5 years before you see any houses going up.
Its a pain as I do a lot of work with builders and building regs, they like to think that if they applied for consent in 05, they can use the regs from then, even though they are only just starting to build, when you tell them they need to comply with the most up to date regs, (which are being updated again in 2013), they seem to think its not fair. (though to be honest, I don't think that will be the case with Barratts.)