Which way are you going? North Africa or Europe?
If you're coming through Spain I might fancy hooking up, if not the whole way at least for a stretch (at the very least for Morocco & Algeria)...
You intending to do a return trip (or just shipping the bike back)?
As far as visas and such go, it'll be very easy going up to and including Turkey for the northern route, Syria-Jordan-Israel-Egypt (due to an official state of war, getting to Israel from Lebanon is currently impossible, so you have to go through Jordan) would be the only problematic bit visa-wise. The other way, no idea for UK nationals, the only person I know that did it was a Syrian/Belgian national (and fluent in Arabic as well as a muslim) and it was a breeze... but that doesn't really count does it?
Anyways, afaik Morocco and Algeria are fairly easy, as is Egypt (quite a few tourists from Europe and such, with bike and overland might be a bit more complicated, but it won't be like trying to get into Burma/Myanmar or anything. Lybia: No idea, honestly... again, don't know any european nationals that have gone there - at least without the support of either an NGO or a company. If you intend to take Tunisia (as in not try to go around it inland), I've heard it's not too complicated visa-wise either, but that info is about a decade old by now (so pretty much useless).
Anyways, I intend to do that (african) route (and beyond) somewhere in the 2010-2012 timeframe, so if that's your path, keep us updated.
"Hope for the best - plan for the worst. Then watch it all go pear-shaped and wing it." - Me
Have a nice trip.