First time solo is always hard; my boy was hard enough and we get on really well. His little sister on the other hand was totally attached to her mum so that was interesting.I'm much less concerned about myself - I don't mind not sleeping the whole weekend - it's more that it's the complete opposite of everything we've done so far. Don't mind jumping in at the deep end, just want to make sure the kid is OK.
It's something you're going to have to do sooner or later. Don't worry about your son, kids are extraordinarily resilient and a night away from mum will be stressful for him at the time but he'll forget about it pretty much immediately.
Try to enjoy the one-on-one time as much as you can and if he gets upset don't let it go to your head. Just soothe and distract and be as zen as you can!
EDIT: and just to echo the previous advice; pushchair or car seat are always a winner!