Like Fanum, I'm a veteran of the Plymouth Dakar Challenge where you take an old banger and drive it down to The Gambia. Half the fun of a trip like this is discovering all the adventures along the way. The organisers of the PDC decided to stop the "old hands" from giving advice to the newbies as it took away a lot of the fun if they were over prepared and over organised.
Although I've done it before I know that Africa changes on a daily basis so what worked in one situation last week or even 10 minutes before may not work now.
Horizons Unlimited is a great resource but can prove frightening for the easily nervous. Tales of kidnapping and hostage taking and or minefields might scare off some people but is all part of the fun. The Foreign and Commonwealth Office FCO has a website with advice on all countries but it is over caution and basically tends to tell you to avoid most African countries because they are full of dangerous natives. Links
http://www.fco.gov.uk/
Fanum's note about the fiches is vital. On our second trip we included a photo copy of our passport info page along with the personal details and the police checks loved that as they had all the possible info on you and they could copy it out into their ledgers at their leisure.
You have to remember to adjust your body clock to Africa time and slow down in everything you do.
I have written a very detailed account of our first trip and I can bring along a copy to the August get together for people to have a laugh about.
The most important bit of advice from the PDC was to leave your egos at home and just enoy yourself with your companions on the trip.
I think the best way to sum up Calum's Road in Scotland to Calum's Road in The Gambia is similar to advice given to Ewan and Charlie on their last trip:
"As you head from Scotland to Africa you will encouter many challenges, corrupt officials, violent natives, armed children, inhospitable climate, political unrest and wild animals.
However, once over the border into England things will improve!"