Anytime I have significant time away from training (mostly vacations), I try to seriously overtrain beforehand. I know that overtraining is usually bad because it maximizes recovery time, but if you're not going to be lifting for 3-4 weeks, overtraining will actually be beneficial for you because you will have weeks to recover. Forget maintaining, you'll actually be growing!
You said you're not hardcore, so this may not appeal to you, because overtraining is grueling, and frankly you have to be pretty dedicated (or a little crazy) to do it. I'm talking two workouts a day grueling. See Poliquin's "Super-Accumulation Program" article for an in depth discussion. Even if you don't want to go completely crazy, I think you should consider overtraining as much as you can between now and your surgery.
If you do overtrain, you'll need to keep your protein at the same high levels as when you train, because your body will need it to recover. Don't think you'll need any creatine during the recovery, since it is really meant to boost performance in training, and you won't be doing any.
Just to sell you on the idea, most people who overtrain and get sufficient time to recover see big gains from it.