my new bits bought ready to b fitted

how hard would it be to fit the satnav?

If you want it done to OEM specs, its rather fussy to do, and expensive; GPS base is around £200, dash loom is £300 (which you can jimmy up and not need), extra cable harnesses are about £120 + the cost of the unit.

Roof lining will have to be dropped too to fit the new base.