Jo, you're clearly not as much a newbie as you may think, and you're definitely not an idiot. The water change was a good move. Leaving the fish in toxic water would not have improved the situation.
Yes, vacuum the substrate and anything else that's obviously dirty. Do what you can to clean out anything that's producing ammonia in the tank.
Then check your water parameters. If you find that your tank is indeed in either a full cycle or a mini cycle, then you'll have to decide how to go about helping the fish through the process. Given your level of concern and how busy you must be with moving, I'd suggest adding beneficial bacteria to the tank as well as using Prime to bind the ammonia, nitrites, and nitrates so they are not toxic to the fish. The Prime will still leave these ammonia and nitrites available for the bacteria so the tank can continue to cycle.
Years ago when I moved my tanks, I used Tetra SafeStart with excellent success so that's the only one I recommend. There may be other good products out there, but I can't vouch for them. This is the stuff I used: http://www.amazon.com/Tetra-77961-Sa.../dp/B002DZG1BW
. Here's some more product info from the manufacturer's website: http://www.tetra-fish.com/sites/tetr...l.aspx?id=4224
All you can do is give the fish the best water conditions possible by giving them clean water, neutralizing the ammonia and nitrites while the tank is cycling, and add bacteria to help the tank cycle faster. If you see any signs of illness, then you may need to treat them with medicines, but only as indicated.
Also, just so you know for future reference, fish do fine without food for a week, even two weeks, and it's generally better to not feed them if you're not there to watch over things. It does not hurt them to go without food during that time. I don't think the vacation feeder caused this problem, but I thought I'd let you know should you go on vacation and need to leave the fish unattended again.