Ford Focus won't start, when does cuta out after 5 mins

Engine won't start with either key's I have. I was advised this could be an immobiliser problem. Had a guy come down with a computer to try it and eventually the car started using both keys. Later that day car wouldn't start again! So today it did start and I drove it for 2 mins, everything fine. Then later it wouldn't start, did start then when driving the car went off! Rang a guy who said to watch the flashing red light and tell him when it stopped flashing what happend, anyway it flashed once then nothing then 6 flashes then nothing then flashed once etc. He says it could be a fuse, but he's unsure why the car cut out. I really don't want to be ripped off at a garage so if anyone has any suggestions pleae pass them to me! No woman driver jokes aloud!!!!!