I did it in 2008 (yes, that year) and have done a few other stage races.
The biggest thing with multi-day races is being able to get back on the bike the next day. I know it sounds obvious, but in your training make sure you're getting a few long back to back rides in.
Some of the guys went to the launderette in Machynlleth on the night we stayed there to wash and dry kit. This seemed to work quite well, but it depends on the route if you're going to be stopping anywhere near a town of a reasonable size.
The bag they provide is big, getting a week's worth of kit in isn't that hard if you think that most of the time you'll be in riding clothes, and the evenings you'll need warm stuff, but it's not a fashion parade so you can wear much the same stuff most evenings.
Couple of tips - the bag you're given isn't waterproof so wrap each days kit in a carrier bag/large sandwich bag before you go, then you won't be searching for stuff each morning. If you can get 7 sets of shorts, socks and gloves it will make your life a whole lot more pleasant, particularly if the weather is bad. Ensure you wrap your sleeping bag up nice and dry as well.
Take plenty of your favourite food, particularly savoury stuff. You'll be fed up with energy bars, gels and drinks mid way through the event.
Food in the evenings was very good indeed, and plenty of it. Snack stops during the day were more variable. As someone else has said, take some cutlery of your own - even some throwaway plastic ones - it's a lot better than a spork.
Footwear - your shoes/boots will be wet on day one and probably stay that way for most of the week. In the evenings, I'd suggest a pair of sandals or crocs. Anything else may just end up soaked and useless, with something simple like sandals you can just towel dry your feet before getting into your sleeping bag.
As for your phone, just turn it off during the day. You can always turn it on if you need it, and if it's you that gets injured, you're probably not going to be looking for your own phone. Some of the campsites have no reception anyway, so again, just turn it off.
I have decided to do it on a HT however 
