my boiler has gone out and will not re light?

My boiler is fairly old and the pilot light has gone out, it will not re light, there is electricity going to the boiler I have checked the fuses and switches and there is gas going to the boiler. I have got a gas service engineer coming tomorrow but I do not want to be ripped off. I have already made the mistake of saying that if it is too big a job, I would be looking at a new system and I think he will go in that direction even if it is a small job. Could it just be the Therma coupling or something like that?