Of course we're not full. Plenty of empty housing in the North - but successive governments (and indeed not just the Tories here) have not done nearly enough to support economic development and have focused exclusively on London and the South.
There's also quite a lot of empty housing in London, just standing there getting pricier and lining the pockets of foreign owners. But that's OK, because they're wealthy.
If we hadn't had 13 years of cuts to education, the NHS and council funds, we would be able to do so much more. There's a reason why those countries who didn't go the austerity route after the crash of 2008 are now doing better economically - austerity doesn't work. We are where we are because of the choices made (largely) by the Tories.