In reply to Hannah m:
You don't need a lot of fitness, it's 3 weeks of easy-ish hikes (albeit at altitude). There's a couple of steep sections on some days, but most of it is a fairly wide & well-established path. Barring some bad luck with altitude sickness I imagine most folk with a basic level of fitness would be able to do it.
If I was doing it again I'd take diamox for the altitude. I didn't when I went and found it tough. On a recent trip to Mera Peak (about 1000m higher) I took diamox and only got a minor headache. This is just my experience, you should read up on AMS before you go & talk to your GP.
Don't worry about base camp itself, you don't normally go in to an actual camp in the Oct/Nov trips (it's just a rock near the camp that the sherpa pick at random) and you'll only be there 15 minutes or so. Any rubbish is further up the mountain. There were maybe 20-30 people there when I arrived with my group, but no-one's hanging around so it's not too bad.
The flight into Lukla is a bit hairy, but it's all good fun. The biggest hazard is the fact that it may not go ahead some days at all, maybe even for a few days in a row. Waiting in Lukla for your flight back to Kathmandu can be frustrating, make sure you have enough reading material at this point in the trip as you can be sitting around for hours (sometimes days).