>as our UK insurers say that they cannot cover us. Also can we pick up the 'Green card' at the Border too ?
I have done this trip by car to Morocco.
True, you can't get the docs in the UK, you buy them at the border. When we did it, you could get docs for one, two or three months. One month cost 600 dirhams, then 1200 then 1800 dirhams for three months.
We passed through the Ceuta border in about one hour after completing all of the formalities. Make sure to secure the customs sticker onto your front window securely.