Spark ignition coil

You can buy these -- I don't know _where_, but the latest Flying Models has a review in one of the columns.

For winding your own, do some web searching, or check the "Strictly IC" web site for a back issue with a pertinent article.

I'm in GB and stuff is even more expensive than in the US. I'm not going to fork out more than the strimmer engine cost me on just a coil for making the electronic ignition.

Already did. I only found one site with instructions, but I think it's for a processor controlled electronic ignition circuit which puts more than 6V into the coil. I need a coil that will work with 6V. I think motorbike coils are too big?

Try going to one of those websites where they sell reprints of old books from the first half of the 20th century. There used to be books telling you how to do or make just about anything. I can't be sure that you'll find what you're looking for, but I won't be surprised if you do.

I think there is a book about coil winding, I'm just being impatient..... While pondering on this I came up with a couple of thoughts...: See new thread "Thoughts on ignition timing".