Ok so do most bike shops do such a thing, or is there anywhere more specific that I can go? Obviously a bike shop is there to sell bikes and I don't want to particularly to ask for a fitting if I can't afford their shiny new bikes... 
Barlist - you've summed up the main concern I have with buying 2nd hand. That and I can miss blindingly obvious things such as handlebars. (!!!)
I have a friend who does tri but he spends most of his time in Cardiff and I spend most of mine in Leeds, so will have to see when he's free...
I think I'm gonna shoot for the Outlaw, it's close and I have a couple of months to start assessing where I'm at with fitness before taking the plunge. Signing up for the Uni gym today so I can take advantage of free pool sessions... 