Biyi Bandele is in trouble. He is perched on a white leather sofa in a plush Toronto suite. The film festival blasts away beneath us; Bandele clutches his coffee with the faintest air of desperation. "There was an after-screening party," he says, "and very foolishly I went. I now have a serious hangover."

The screening was the premiere of his feature-film debut. Half of a Yellow Sun is an adaptation of Chimamanda Ngozi Adichie's Orange prize-winning novel. It's the other Chiwetel Ejiofor film at Toronto this year; and though 12 Years a Slave dominated headlines, Sun was met with a rapturous reception by a substantial crowd that included many of Toronto's Nigerian expat community. "I had the writer of the book in the audience, I had all the major stars from the movie, some of whom were seeing it for the first time," says Bandele. "At the end, I was essentially relieved."

Listen to him tell the story of the production of Half of a Yellow Sun and his anxiety becomes even more explicable. The narrative spans a decade and weaves personal histories through the depths of the Nigerian civil war. It was to be shot on location in the southern Nigerian city of Calabar. But with just weeks to go, all plans were torn up, and the shooting schedule slashed from eight to five weeks. Line producers were brought in to hack out scenes.

"These guys didn't even read the script; they just looked at the shooting schedule and went: 'Night, night, night – no, we can't do that.' So I had to rewrite a lot of scenes and try to find a way of smuggling the essence back. Fortunately I started out in London fringe theatre where you had a budget of, like, minus-£50 to put on a show. So I wasn't daunted."

When the shoot finally began, the drama didn't stop. "Myself and several members of my crew and cast got typhoid. Some even had malaria. Thandie Newton got typhoid too, but she was incredible. She was really suffering but didn't take a single day off work. It was like she was possessed by God knows what. The experience of shooting was tough, but every single day I woke up and wanted to be on set, because you just didn't know what was going to happen."

Bandele, 45, has a winning smile, a hoarse laugh and greying dreadlocks tied behind his head in a bunch. That he was excited by such apparent traumas fits with a life that saw him move out of his family home at 14 and straight into the Nigerian gambling underworld.

"I come from a pretty middle-class slash upper-middle-class background," he says in qualification, "but I started reading Hemingway as a teenager and got the desire to travel. First I moved into a friend's house a few streets away with a bunch of friends, and then I started to travel around Nigeria and I got a job with a Lebanese guy who had a kind of gambling empire in the northern part of the country. I was in charge of 40 'pools houses' where people would come and bet on the football pools. It was illegal, but at the same time we had police escorts to guard us because we were taking in so much money."

This nefarious lifestyle came to an end when Bendele was "quite literally stabbed in the back". He headed south to university and concentrated on his writing, which eventually took him to England. "In my first year I wrote a play which I entered for a competition sponsored by the British Council," he says.

"Two years later I heard that someone had heard my name on the World Service. Shortly after I got a letter saying that I had won this award. There was a reading of my play at the Stephen Joseph theatre in Scarborough, Alan Ayckbourn's theatre, and I was invited. The British Council flew me to England, and within something like four weeks I had a publisher and an offer of a job on the arts desk of a weekly Nigerian newspaper in London. This was 1990, and I've basically been there ever since."

In that time Bandele has become a published novelist and garlanded playwright working with directors such as Danny Boyle. Now, with Half of a Yellow Sun, his own creative vision is finally up on screen. As for his actual vision, however … well, that might still be a little blurry.