Route is doable, no big probs. French airspace looks intimidating at first glance - until you realize that most mil airspace is very low-level. Get one of the French charts that depict the VFR 'corridors' and you'll be fine. Avoid fuel stops at lunch hour, though....
Spain: be aware that AENA has hiked the landing fees. At most airports they are still reasonable, but have a look at their website (free registration) first.
If you land at Girona, refuel before parking - the bowser is at the opposite end of the field to the transient parking area!
Heading south from there, you have several options where to stop/refuel. Program the Barcelone VFR route into your GPS and have a good lookout in the Sabadell area - unless you land there you'll be overflying a very busy airfield with lots of training! Only place to avoid at pretty much all cost is Valencia - expensive landing fees and mandatory handling! Alicante is nice. There are also a few smaller fields (like Muchamiel near Alicante), but check Avgas situation with them first. Download the charts from the AENA site and have them handy - the VRPs in Spain usually have two names, i.e. an 'international' one such as N1, and a local one. Both are on the charts and Spanish pilots will mostly use the local ones. Helps with situational awareness....
Gibraltar: This one's a bit tricky. They need 24H PPR (could also be 48H, not sure right now, don't have docs to hand). They will fax or email you a few documents, mainly pertaining to their arrival/departure procedures and, specifically, the windshear there. This is NOT to be taken lightly - the Monarch and BA flights to Gib quite regularly divert to Malaga. What's more, you need to leave Spain from a customs field. In the South, this means Granada, Malaga, Seville and Jerez. Be aware, that Malaga is IFR only Thur-Sun inclusive for most of the year. Check the NOTAMs.
Realistically, I would probably avoid Gib and do either Granada or Jerez to Tangiers. Contrary to some myths, you do not need to land there, but it's your best bet to get info re Moroccan airspace and routes. Take a WAC chart and copy the routes off of their wall chart there.
In Morocco you have to fly VFR routes (see above). Casa isn't much to look at (and the route along the coast is rather boring), much nicer to go via Fez. Avoid landing in Tetouan, though, must be the most unpleasant airport in the whole country. Be aware, that overflying any of the royal palaces is a big NO-NO in Morocco (this includes the city of Fez).
Marrakech is a big international airport, no probs there.
Enjoy!