In reply to Tony the Blade: I recently (2 weeks ago) had to attend an interview because I've been to Sudan, Afghanistan etc etc.
Clearance is not a given as the guy in front of me in the final queue was denied a visa, but he was Russian and had applied for the wrong sort of visa.
STart the online application process now, or tomorrow at the latest, and (although it's a little annoying/frustrating) get through it and get an appointment booked ASAP.
They will tell you on the day if you have been successful or not, and if not then why not.
It took 7 days for my passport to come back with a lovely 10 year visa in.
If you have any questions about the visa process on the website then it's all fresh in my mind and I'd be happy to answer any questions. If you pm me we could swap numbers and speak in real life.
Otherwise, be honest and croos your fingers.