If you're only burning wood, sprinkle the ash around the garden on the borders. If you burn coke or coal, ash from that should not be used.

Wood ash contains potash so encourages flowers and fruit, so put it around your fruit bushes. Not round raspberries though as I believe it tends to make the soil a bit alkaline.
Do not expose it to rain before you spread it as the potash is very soluble and will wash out quickly.

If you are burning a mix of wood and anthracite you can put on your paths to keep the weeds down but it looks very messy. Have to confess ours goes in the wheely bin. When we are only burning wood Bulba. collects and uses on the veg. patch.

thanks for your help