All soil needs to be replenished in the winter after a busy growing season having depleted all the nutrients but it depends on what you are going to grow next year – this will dictate how you should improve your soil. Brassicas and legumes love soil that has been enriched with well rotted manure and organic compost however root crops such as carrots, parsnips etc. prefer a sandier lighter soil with no added manure as this will cause the roots to split.
Green manures are excellent crops to grow in any soil that is not being used in the Autumn/Winter months, this can be dug in and valuable nitrogen added back into the soil. Some overwinter and some are killed off by frost so check before you buy.
Strulch is very good at holding in the moisture, keeping the weeds away and deterring slugs and snails however it doesn’t contain any feed. Strulch is added to all the beds in Stephanie’s Kitchen Garden at the planting up stage and then dug in during the winter months.
I would add well rotted manure to your beds in the New Year and it will work it’s way into the soil, lightly dig in any left over in the Spring. If you cannot get your hands on any well rotted manure, Pelleted Poultry Manure is a good alternative. If your beds need topping up you can add compost either from your compost bin or bought in. Harrod Horticultural can supply Rolawn Topsoil & Soil Improver if you need to buy in bulk.
I hope this helps – good luck!