There's some great advice in this guide on how to protect your more delicate plants, including using mulch and fleece to insulate them. The effects of frost and cold damage can be devastating to a carefully tended garden, although surprisingly snow can be a good thing, due to its insulation effects. Beware of heavy deposits on the roofs of sheds and greenhouses though!
One of the jobs you simply must do each year is to protect your garden furniture. Make sure it is cleaned properly, before protecting the wood and then storing safely away in a shed or garage, if possible. This handy cleaning kit from Alexander Rose contains everything you need:
Keep a look out too for hedgehogs who may be seeking shelter under hedges, snuggled into piles of leaves, and in bonfires etc. Contrary to popular belief, they do wake several times during their hibernation period, and will sometimes use this opportunity to move to a new nest. But if you see a hedgehog who seems disoriented or is staggering or wobbly, phone your local wildlife hospital for advice as it may be suffering from hypothermia. You could always invest in a special hedgehog nesting box to help do your bit for the cute little critters too: