Unless matters have altered since March, you will have to either arrange insurance for the eleven nights before leaving the UK, or cough up the full month's premium on arrival at your port of entry.
In any event, the insurance I bought at Tangier Port for a full month, (14 nights in Morroco), was in all probability absolutely worthless beyond allowing me to comply with entry regulations.
If you can get insurance here go for it, (one of our group took out a new policy with a company who cover Morroco and, "lost, a month's cover on his existing policy).
All the best, Jim.