This post is slightly out of order, as I installed the hose after mating the bell housing, gearbox and engine. It's a short entry and so I'm adding it now.
The recommendation is to install the top radiator hose before the engine goes in.
Fitment of the hose is pretty straightforward although it is a tight fit. I used the smallest amount of silicon lubricant just to ease the hose onto the target port on the back of the engine above the bell housing. Don't forget to put the jubilee on first.
I like others such as https://www.purplemeanie.co.uk concluded the supplied 40mm jubilees were just to small, I mean impossible. I already had some quality jubilees and so opted for a 52mm which made for a perfect and easy fit.
I'm not sure what Caterham's logic is for supply 40mm, cost? May be an email to Derek to clarify.
I'll rotate the jubilee round for the perfect fit once the engine and other auxiliary items are installed.