Is it easy to replace the rear light in a zafira?

during the night some kind soul clipped my rear end and broke the glass/ plastic cover on the os rear light unit. The lighting unit comes in one piece and contains brake, indicator, reverse lights all in one. I have found a replacement for £40 but cannot really afford to pay for this to be fitted. Does anyone know if it is fairly easy to do??? My manual shows how to change the bulbs and this seems to indicate that the whole unit can be removed... but am reluctant to try. My Dads's 'Leave well alone' is ringing in my ears!!!