As far as I know, it doesn't close.
But be a bit forewarned; if you go down there at midnight on a Friday night you're going to run into either neds drinking/smoking/etc or the after effects (ie. a barrage of bottles / smashed bottles and half eaten curries). It's perfectly possible to get through though; you just need to be prepared to slow down and smile at them.
(The south bound tunnel is closed atm btw... and if you fancy it I'm sure it's only an extra 2 miles to go via the squinty bridge instead, and it's a fairly straight flatish run too, so overall only takes an extra 10 minutes if that.)