I'm departing for Morocco Jan '06.. will be the 11th time. I was based in Gib for several years in the Navy. I'm not going to give you a load of advice, you'll work it all out for yourself and have a much better time in doing so.. All i will say is "Not alone", We used to buy £200 hacks (XT's, KLR's..) off the local kids over the border in Spain and spend our leave time in Morocco. But never less than 4 of us, Past the Rif Mountains (which is a baptism of fire) and you'll be fine. Find a truck driver at your port of entry I assume you'll be using Tangier, $10-$20 and he'll chaperone you through, You won't miss them, look out of fruit and veg! Over 150 8ton trucks cross the straights every day. Stick in amongst them.. Infact for 20 he'll lend you his daughter on the other side.. Carry dollars as a means of getting a better deal, Euros are fine, but are usless when trying to swop for a little local currency.
These are just my experiances, you'll have the time of yourlife. Remember one thing.. Kef or Hashish as we know it is rife you'll be offered it everywhere. Possession alone will leave you looking down the barrel of a 20 year stretch. Some will offer you it then shop you to the rozzers, just not worth it, I've seen it happen. Oh, and stay away from Morrocian held west sahara!
I can put you in touch with some lads in Gibraltar if you let me know the exact date of travel, they go over every few months or so for a couple of weeks.