Re: New to the GTV club
The ribes only undo the head covers... they are usually very loose and to be honest you could probably undo most with a suitably sized flat screwdriver if you were cairful. Most people use torx bits which whilst different still work OK. Buy yourself a cheap set from B&Q or Halfords, one will fit. What that precise size is however I have no idea, for me it was the one that fitted!
What you will need if you're doing even the smallest amount of DIY is a very decent allen key / hex head set, they're everywhere and all shapes and sizes. Get a kit for your socket set / wrench, will make life easier than using normal allen keys all day. Plus, a set of those will almost certainly come with the torx / ribe bits as well.
What are you changing?
If its the plugs on a TS you also need the slightly less common smaller spark plug spanner size... again, what size that is I can't recall, just the smaller of the two.
Hope that helps,
P.S. Search the archives in this forum and you will also find links to download a PDF manual. It takes ages cos it's in 5 bits and there is a limit on how often you can download without paying, but, once done, that should satisfy your need for detail once and for all...