If it is pure wood ash, I would bag some of it up and wait until the early summer to use it around fruiting and flowering plants. It will contain a little potash (potassium) but beware too much will make your soil very acidic.

I'd leave it to weather over winter. but I understood it to raise the pH which will make the soil more alkaline not acidic. Potash is potassium in a water soluble form. which is usually an alkaline solution.

Agree sbg peat will boost acidity

Many thanks for the answers.

Quite right SBG, I stand to be corrected but I would keep it covered as winter rains will wash away any potash present.

potash is a good nutrient as it helps the plant to also take up nitrates so some in the soil will be advantageous.