If you really do have honey fungus, you can't kill it off - it kills your woody plants instead. How toxic it is depends on which particular variety, and the only way you know is how rapidly woody plants die off. Once its in, it's in, and the only thing you can do is remove anything in its path which is susceptible to honey fungus, including any dead tree or shrub stumps and any dead wood lying around, and replant with things which have shown a degree of resistance to honey fungus, or soft stemmed plants.

I did read somewhere a long time ago that you can dig a trench around the outer limits of the mycelium ( not sure how you can be sure where that has reached!) and put Jeyes fluid in it. If you google honey fungus Jeyes fluid there is lots of info. However I think they have changed Jeyes fluid recently so don't know if it would still work.

I would be inclined to remove any infected and dead wood, and look for resistant plants as already suggested. I would dig a hole and remove completely any of the old soil. Use Armillatox as a soil drench. Replant using 'clean soil' using 'Rootgrow' as a barrier against any future infection.

I'd never heard of Rootgrow Jimmytheone - sounds very interesting. This site is great for learning new stuff!

Rootgrow's good if you want to plant roses where roses were previously growing - gets round the problem of rose sickness, Steragram. I used it this summer in just such a situation, but nothing I've read about it suggests it helps with honey fungus. Also supposed to be good generally for new tree/shrub plantings, but it would work out quite expensive if you used it all the time.

Thank you Bamboo!