Having personally just done this job myself, I can confirm it isn't the easiest of tasks.
Plenty of sensors (it's a Nissan!) which need to be marked up on removal of wiring loom (unless your a micra genious), and hardly any space in the engine bay.
Easiest procedure is to remove the whole engine - which involves removing the exhaust, BOTH manifolds (not enough clearance to lift out otherwise), alternator, radiator, etc etc. Believe me, I tried it without removing these parts.
Total time to remove engine around 4 hours. It's definately a 10 hour job for most mechanics, although rushing it could get it done in 8.
Expecy to pay around £1200+ inc parts, although I managed to get the whole chain kit for around £200. I charged £600 all inclusive of new oil, filters, chains, etc - which isn't bad compared to other peoples prices - probably as I don't have a shiny showroom to upkeep!
Anyone needs the job doing - I'm in Sheffield. Zero 778866 zero 377
K12 expert :0), April 2010