When you have a work trip, unless you're a struggling charity or something, you expect work to pay the £100 for a Premier Inn or whatever. (I wouldn't be surprised if the guy pocketed the expense money or split it with OP's partner).
Boundary 1: Asking to stay at the home of a colleague you've never visited before instead of paying for a hotel. That's social boundary 1 that he's broken.
OP retreats, & allows this to happen.
When you're imposing on someone, the unspoken social rule is to be as little bother as possible.
Boundary 2: Arriving 5 hours early, inconveniencing the hosts.
OP retreats, & allows this to happen.
Boundary 3: OP said just drop your bags off.
Guy: No. I'm going to wait here.
OP doesn't push back, but allows him to stay.
Boundary 4: OP says please leave.
Guy: No.
OP retreats, & allows this to happen.
Boundary 5: I'm working, don't disturb me.
GUY: I'm hungry.
OP pushes back and says no. I'm not making food for you.
MUMSNET PEOPLE: This guy is breaking a lot of boundaries. Worst case scenario, boundary stompers can get a bit rapey. - this happened to me/my friend.
OP pushes back. You're just fear-mongering, mean bitches.
Well, even if OP refuses to engage or provide an informative update, maybe others can still learn from the situation.