Not a huge deal. I’ve coached many athletes through similar interruptions and they’re always pleasantly surprised. You’ll want to reduce your run volume and increase your bike and swim volume immediately before and after your vacation. Nothing radical, but enough to attenuate your losses. And if you happen to have a set of resistance cords, take those with you to keep your swimming muscles in shape.
Plan selection shouldn’t really be based on age or performance level. Instead it should be based on your personal training history and schedule. You’ll want to choose a plan that stretches you a bit but that you know you can handle. With our level guarantee, you’re not stuck if you choose a poor fit initially.