be carefull with duffels.. if it's a standard navy C bag (most likely), remember that although they hold a lot, they are not designed for long distance.. generally they were meant for ship to ship transport, and not camping or other survival.
the have no vertical or hip support, pull heavily from the shoulders back, and are hard to balance..
i landed in france & went through a bit of england with one, many, many years ago..
the worst decision of the trip, perhaps... wound up ditching it in Folkstone & re-outfitting completely..
this is *not* something you want to hike with, at all, ever, unless you rig an effective frame of some sort, or everything you have is super-light..
you run the potential of damaging your back, if you try to hoof any number of miles in it.
Guys who are over 6' & stiocky may be ok, but if yer like me, at 5'6", it's not a good ratio..
if it's a shorter dufflel, like a gym bag or some such, you should be ok, but standard issue is, i believe, somewhere around 48".
anyways, if yer just out for 2 weeks, you shouldn't need too much.. a cheap pack, at a thrift store for 10 or 15 bucks, if you can afford it or ask for it as a donation, will do you far, far better..
don't take anything super important with you, either, if yer def coming back.. no more than your communicator..
good luck, though, & i hope you have a great trip!!
: )