You'll find the transition from late autumn into winter from a bird perspective little different, just colder.
From an Essex perspective:
Brent Geese will arrive from mid September peaking in early October with many thousands staying the winter around Old Hall, Leigh, Wakering etc
Passerines will arrive that will over winter in varying numbers such as Redwing, Fieldfare, Brambling, Snow Bunting etc whilst you may notice an increase is some species you;ll already be aware of such as Song Thrush, Skylark, Meadow Pipits, Stonechats.
Waders are in motion now and will over winter in large numbers, such as Dunlin, Knot, Bar-tailed Godwit, Sanderling, Turnstone whilst species such as Black-tailed Godwit will concentrate on traditional wintering areas, Benfleet Creek. Others such as Greenshank and Spotted Redshank will dwindle with only a few around.
Gulls will increase in numbers with Kittiwakes more and more regular from late October around the outer Estuaries. transitional species such as Little Gull and Yellow-legged Gulls will be few and far between. White-wingers such as Glaucous and Iceland Gulls usually have their peaks around mid February and March though a few will be around from December time with locations such as Rainham and Pitsea being the prime locations in the county.
Other Wildfowl are now arriving, Pintails, Wigeon, Teal, Pochard, Tufted Ducks and will peak during the winter. Goldeneye, Red-breasted Mergansers, Smew, Goosanders start appearing from end of October.
Divers and Grebes will be at a peak around November and then again mid March unless theres bad weather then the estuaries such as Blackwater and Thames will seen concentrations with Southend Pier being especially good for seeing Great Northerns and Red-throated Divers and February is usually good for Black-throated Diver and Slavonian Grebe whilst Red-necked Grebe usually has its peak around this time.
Winter woodlands, especially in the new year can produce the usual woody stuff but increased chance of Hawfinch in some areas. March is usually good as Lesser Spotted Woodpeckers, Treecreepers and Nuthatch all become more vocal.
As with everything weather is a dominant factor and even if the weather is harsh here in the UK it might not mean movement or influxes of birds, more than likely they'll be leaving these shores. We need very cold conditions on the continent to drive the birds over here and freezing conditions over there will see big increases in the wetlands, fields, parks and woods here.
Given the right conditions in Jan-Mar Southend Pier I would recommend as you could get excellent views of Med.Gulls, Kittiwakes, divers, auks, gulls, seaduck, Purple Sandpiper, incoming tide is best and to be there at least 3hours before High Tide to see birds get pushed up river.
Great Northern Divers can sometimes show this well
http://www.birdersplayground.co.uk/Divers 1.html
Purple Sandpipers this well
http://www.birdersplayground.co.uk/Waders 3.html#Purple Sand
MedGulls this well
http://www.birdersplayground.co.uk/Mediterranean Gull - adults.html
Auks this well
http://www.birdersplayground.co.uk/Auks.html#Guillemot
You'll be hard pressed to get views like this anywhere else in Essex.
If birds perform like this over the coming winter period I will post here.