Righto. My google-fu lead me to consider a vacuum leak, so I just went out and had a look at all the hoses. It was all looking good until I found this:
I don't know much about this stuff, but the fact that it goes into the throttle body suggests to me that it's almost definitely the culprit. The hose is quite short and at a tight angle, there is no room to trim it, and I'd guess it's been under tension for a while before it's ripped. I'm guessing that I should be able to get a replacement hose at any car parts place right?
Could the car be driven as it is? I ask because my wife is going to go into labour at any second, and it's our only car. It'd be a pretty interesting Uber ride otherwise.