Mild days can lull the allotmenteer into a false sense of security but the soil on our allotments is heavy and attempting to dig and work waterlogged soil will only end up compacting it.  It is better to stay off it, pick out the larger weeds that may have appeared and otherwise stay indoors.  You can order seeds you want for the year and possibly start off a few in a heated propagator.  Get your seed potatoes and lay them out to chit in a cool, light room.  Buy shallot and onion sets for planting in February and March.  Finally spend a bit of time sketching out what you are planning to grow and where you intend to plant it.