Riggsy,
I'd be shocked if Excel could predict which plane they'll be using on Friday 16th. They have several to choose from and it's hoped that at least one will be available for you that morning - but I wouldn't guarantee it.
You can look at
http://www.caa.co.uk (civil aviation site) and select, from the upper left of the screen, the Searching CAA Databases link.
Then click on the link
http://www.caa.co.uk/ginfo and when the screen offers, enter Excel in the Registered Owner field. You can repeat this excercise for Air Atlanta - but not many shown. I believe some of their planes are registered in Iceland.
This is a useful site showing the U.K. registered aircraft and their technical specifications, weights, configurations, ages, flying times and insurance requirements. There's even photo's for the anoraks.
This site only shows U.K. registered aircraft and doesn't (yet) disclose technical fault logs.