Knock or Crank Sensor

Hi all,

So to start, it's a 1998 1.6 8v GL 5 door. A few weeks back it was having trouble starting which I put down to battery as I knew it was on the way out. Then it wouldnt start at all. Was getting the odd fire and puff of smoke from the exhaust but wouldnt turn over.

RAC came, checked coil pack said it was fine. Checked rota arm, cleaned it up a bit. Ran fault checker and said it was saying crank sensor. 

Towed to garage who when they started looking at it, said it was in dire need of a service, which it was, so they did that, new battery, plugs filters etc and then called and said it seemed to be fine now.

Picked it up, drove it home. Was fine until yesterday when it wouldnt start again. Called garage and asked if they ended up doing the crank sensor. They said no as it doesnt have one, only a knock sensor. 

Much as I dont like to question professionals, and he is a really sound and knowledgeable guy, I'm sure I've watched a video of a guy changing the crank sensor and without one how is engine speed etc known?

He said it is likely dizzy or leads problem. Does anyone have any ideas or know about the crank/knock sensor question? It will crank just not fire. Battery brand new, plenty of fuel but not starting.

Cheers, sorry for long post