Put up any new birdboxes this month so that birds in your garden have time to get used to them and are encouraged to move in. Check on the needs of the birds species you wish to attract and site them accordingly.
Think about whether you actually need to sweep up those fallen leaves off your beds. Yes, go for it if you want to use it for making leaf mould. But if you are only doing it for neatness, then consider leaving them in place. They will act as a insulative mulch layer to many plants especially ones that naturally grow under trees and will slowly degrade helping to improve soil structure and nutrients level.
Take a gander around the garden looking for any signs of damage that can be put right easily and quickly with prompt action such as gaps in the soil around newly planted trees and shrubs that have been opened up by windy weather. Just gently firm them back in but be careful not to press too hard and reduce the natural drainage channels in the soil. Stake any tall plants that are prone to damage from wind rock.
If the weather and soil conditions are right, that is the ground is not waterlogged or frozen, you can happily plant trees and shrubs while they are dormant. There is less watering and aftercare to do too.
Again if the ground is not wet and frozen, consider adding a layer of mulch such as Melcourt Sylvagrow peat-free compost around your plants. This has many benefits including improving soil structure, keeping the warmth in the ground, reducing soil erosion and keeping weeds in check.
If you have done all these, it is definitely time to up sticks, grab a hot drink and settle down with a book in the warm.