In reply to Jaomes:
We couldn't find any companies in the UK that would insure our car for 6 months in Morocco, but it's not a problem as it's super easy to get insurance on arrival.
First off, make sure that you've got your car registration doc and licence with you when you go. You also need an import form, which it's worth filling in online and printing out before you arrive in Morocco, so that you can hand it in at the border. I think you can find them (and more info) here...
http://www.morocco-knowledgebase.net/forum/showthread.php?t=73
As for the insurance, you can purchase this for your car once you have cleared customs at the port. It's not as cheap as other places in country, so for a long trip we bought 3 weeks' insurance at the port, which covered us until we went to a local insurance company. For a 4 week trip it might just be worth getting it all at the port.
Insurance was pretty straightforward in Morocco, though not cheap. It's way simpler than in the UK as it's the vehicle that's being insured, not the driver... so no long forms about your history!
Overall, the whole process of vehicle import was pretty simple, and I'd do it again. Worth being fairly chilled about timings though - just accept that there will be queues at customs and officials are in no hurry whatsoever, so don't expect it to be a quick process. We allowed a day from El Chorro down to Tanger, and made it to a hotel in Tanger by dinner time.
Driving is fine in rural areas and on motorways, but I'd avoid driving in big cities! Marrakech is a nightmare!
Have fun!