The trip is easy Ive done it several times. Algeciras I believe now goes to Tanger Med, not done that, but from the ferry terminal in Algeciras you can get a free bus transfer to Tarifa, a pleasant journey, and get the fast crossing which brings you into the port in Tangier, just below the Medina...Fantastic. Easy to get the bus from Malaga airport to Algeciras to, or indeed the other way. I originally did this to avoid flight cost to Morocco, but I no longer have to travel to London, as flights now go to Marrakech from Bristol, and are dirt cheap if you time it right. I Have no idea how long you have, but would recommend a couple of nights in Tangier, which I love, and visiting Chefchaouen, which is easiest from that end, Three nights maybe. If you haven't been to Morocco before, I would continue to Fes, and visit Volubilis and Meknes fron there as a base, and stay four nights. Then Head to Marrakech, by train or desert tour, depending on time. Marrakech you could spend a good while, or head out to Essaouira, and return from Marrakech to Tangier on the Sleeper. Or fly our of Marrakech or Casablanca. You can also fly out of Ouarzazate these days, so if a Southern Morocco tour was of interest, that could save you time.