The Home Brew Company has a wide range of crystal malts. This is the one you want:
http://www.thehomebrewcompany.co.uk/crystal-crushed-grain-500g-145-ebc-p-141.html
There is little clarity on where pale crystal ends and medium crystal begins, or medium crystal ends and dark crystal begins. Home Brew Company does a 113 EBC crystal that I would say is on the borderline between pale and medium. And medium becomes dark somewhere around 200 EBC I think.
Yet another colour confusion is the existence of a third colouring system, SRM. 145 EBC is about 75 SRM, which is what you need for this recipe, not 75L. Dunno why there are 3 systems. Does my head in...
Thanks mate... It does seem a very confusing system with having 3 different methods :/
I have ordered all bits so will be ready to get my first AG on Saturday hopefully :)
I ordered the 145 for this recipe, thanks again for your help. Will keep you posted how it goes! Cheers