I wouldn't start with something you're not willing to continue doing, that is if you offer milk in the middle of the night as a quick fix then it might become an issue itself that can take long to break.
Have you tried white noise or some other type of noise to mask lo's cries? i live in a pretty loud neighborhood (lots of teens hanging out till late hours in the night, lots of doors slamming... you get the point). I put on baby einstein's and raymond lap's music on from the moment i start wind down for lo. It pretty much masks any outside noise (or at least makes it less stressing when for example are fireworks or something, the music on helps ds not to wake so soon). Some moms around here with your same problem have used white noise machines or even fans (not really what i'd suggest in this weather LOL) to mask outside's noise.
You can also talk to Jack about how Luke's a tiny baby who's likely to wake for some time on, so he has nothing to fear/wake for in the middle of the night. Give hima comfort object (blankie, stuffed animal) who will keep him company in the middle of the night: if Luke wakes you, hold teddy and help him go back to sleep. Talking to toddlers about stuff during daytime helps enormously to sort out night issues. They understand so much more than we can think of, and are able to remember even when they're half asleep... and it makes no harm in trying right?
HTH and keep us posted!
