You can get insured for Maroc for your bike either in the UK or once you get there. I recently went to Maroc/Mauri with a friend and I did the former (got it here) and he did the latter. My insurance broker (H&R insurance in Aberdeen) were fine about extending my green card to cover Maroc (cost 21 quid I seem to remember)- but they were less interested in Mauritania and Senegal!!
My mate's insurance - issued at the ferry port in Nador cost him about 40 quid. We didn't have any problems with paper work, though you must fill in a temporary imporation document which you can get from the Customs official who will normally be on the ferry itself. To get this, you need to show him your passport, V5 and green card.
hope this helps
(04 KTM 640 Adv 'Naartjie'/11 KTM 990 Adv 'Tsumeb')