That's an amazing reply, thanks for taking the time to do that. Sounds like AT can still be done in a day then. Is Charlie worth doing? was not there when I last went. Also are the gardens in any better condition these days? back in 05 they were left to ruin.
Before any elitists see this, let me just say that contrary to one sided opinions, Charlie is a good ride and very worth doing as there is hardly ever a queue. Now thats out of the way...
Let me just say that it would be highly recommended to get a hotel, as trying to do everything in one day is possible but will probably just stress you out and make you feel rushed and severely hinder your enjoyment of your day. Plus you can get a come back tomorrow ticket for £9 each.
I would recommend trying to either get a Smiler fast track or doing it in early ride time, and while you are in X Sector then I should warn you that missing Oblivion will get you shunned off of Towers Times Forum. If you end up with a spare 20 min after doing X Sector I would suggest doing Cbeebies Land during early ride time as while aimed at todlers, Mr Blooms Allotments is quite good. I also recommend going on In The Night Garden Magical Boat Ride and pretending that it is a delibrate sattire as it genuinely works and is very funny.
If you are there for more than one day, then make sure to watch The Kidnap of Lady Victoria Sponge, it is Helerious and I cannot recomend it enough, also while in Mutiniy Bay, make sure that you ride Marauders Mayhem as it is definately one of the best of its' kind in the UK.
Also make sure you go on Runaway Mine Train, as while it is not very thrilling, it is still very fun. While you are in the area also make sure to ride Duel as it has got infinately better since 2005.
I can't really say much about Forbidden Valley, as the only ride there I have been on is The Blade.
Haunted Hollow was new for 2008 so you have never been in that but honestly its not very good, but if you want to get from Mutiny Bay to Gloomy Wood or vice verser, then you can use it as a short cut (but the Skyride is faster).
Make sure you ride Th13teen as it is very very excellent also I highly recommend Hex and Charlie, as they are both very good rides.
I would recommend that you try not to heavily plan everything about the day as if you make a plan to be on Nemisis at 3pm then you will go out of your way to get there resulting in you spending less time on what you were currently doing and enjoy the day that tiny bit less, instead just go around the park at your own pace and have as many re-rides as you want because even if you miss Smiler by spending all day on Nemisis as long as you enjoyed your self then its ok.
I hope you enjoy your trip to AT.