I can't believe no one posted a reply.
I was thinking about what you posted, and I have some thoughts that might make you feel a bit more comfortable. Hopefully.
If you wanted to ensure he wasn't even tempted by another girl then go out of your way during the rest of his time at home to make sex extra special for him. Prove to him he's got something special at home that he better make damn sure he keeps.
Another thing you should remember is that even if there are good looking girls around, they aren't you. I'm sure you've been out before and have seen a good looking guy. You might think he's cute, but push comes to shove, who would you rather be with? Count on the fact that your bf wants to be with you, no matter what anyone else looks like. And he's not going to do anything to jepordize that.
If you're really feeling insecure, then ask (blatantly) for some reassurance. State it all upfront. Say "I know how great you are and worry someone else will see it too, and I'm feeling insecure and need some hugs and kisses right now." Whatever will sound most honest to you. But don't let the insecurity take over, otherwise you'll smother him with it. A little is okay. It'll make him feel special. Too much will cause the opposite effect.
Make a commitment to a hobby or something to do during the two weeks he's gone. Something you've wanted to do, but haven't had time. Or just something you enjoy doing. Otherwise you'll obsess about him the entire time and utterly hate the next couple weeks. Spend time with family, friends, your dogs. Find fun, even if you have to force yourself to do it at first. It'll make that little voice in the back of his head say "Hey, she's not dying without me around, maybe I better make sure I keep trying to keep her interest." It's essential you do this. It'll help keep your sanity, and give the two of you more to talk about when you do talk. You are still your own person, and that's what made you interesting to him before. Don't lose that because you're depressed he's away.
Maybe you could think of his trip as a recon mission. He's scoping out the best places to take you when the two of you do go there. Just because he'll be there doesn't mean the two of you can't go there together at a later time. It's always different when you take your SO because its with the person you love. You see things differently, experience it differently. So even though he may be going there by himself, it doesn't mean the two of you couldn't go later. But when you do go, you'll know where to go, how to get there, and many of the other things that cause hassles on vacations.
Last point... There will always be someone better looking then you. But there will never be anyone just like you. He's with you for the whole package and not just a body. You have to trust that you are worth it. Have confidence in yourself and who you are.
Worst case scenario. Grab his penis, tell him since you're leasing it for the duration of the relationship, that no other girl better touch it or you're putting the slap down on her.