You have got several options:
1) Hired in by Network Rail - Miniature snow plough fitted locomotives. These tend to be older BR era locomotives fitted with a three piece snow plough fitted below the buffer beam. They tend to operate independently, at the direction of the control centre, to clear snow on the railway. They are most effective on snow up to a depth of 30cm but can clear up to 45cm if required. At present I think DRS & WCRC class 37's are out and about undertaking these jobs. You can see a DRS example here:
http://www.flickr.com/photos/intercitygbrailsphotos/8393131760/in/photostream
2) Network Rail - Beilhack Patrol Ploughs are used to clear drifts up to 1.8m high. They tend to operate in pairs sandwiching a locomotive and run at up to 45mph. They are based in Doncaster, Carlisle, Wigan and in Scotland. Here is an example:
http://www.flickr.com/photos/37114/6546321589/
3) Network Rail - Independent Drift Ploughs were constructed from stream locomotive tenders. There are several based around the country and are used to clear the biggest snow drifts. They tend to operate in pairs sandwiching 2 locomotives and run at up to 45mph. They are based at Tees Yard, Doncaster, Peterborough, Bristol, Inverness, Slateford (Edinburgh) Carlisle, Margam (Port Talbot) & Tonbridge and are used to clear the biggest snow drifts. A picture is here:
http://www.flickr.com/photos/36034969@N08/5139687880/
4) Network Rail - Beilhack self-propelled rotary snow blowers of which there are two, both based at Slateford outside Edinburgh. They operate at up to 40 mph and are quite impressive when in operation. Here is a picture:
http://www.flickr.com/photos/darlo2009/7404518940/
5) Network Rail - Snow & Ice Treatment Trains are based mainly in the south east to cover the south eastern region. They consist of a snowplough wagon, sometimes a support wagon then a locomotive and finally a de-icer wagon. This wagon delivers a warm anti- icing fluid to prevent ice forming on the third rail contact surface. Theere are 6 trains, 4 at Tonbridge and 2 at Eastleigh. There are some pictures here:
http://www.ontrackplant.com/photo/997095920028-1 &
http://www.ontrackplant.com/photo/997095940026-1 or here:
http://www.flickr.com/photos/47826/8384979728/ or here:
http://www.flickr.com/photos/60854097@N06/6777566227/
6) Network Rail - GLV de-icer vehicles. These are former Gatwick express luggage vans converted to lay a de-icer fluid on the conductor rail in the south east. There are 4 units that operate in pairs sandwiching a class 73 electro-diesel locomotive. There are some decent pictures here:
http://www.southernelectric.org.uk/tocnews/nwrn_glvdeicers01.html
7) Network Rail - Windhoff MPV units run a number of anti ice patrols mainly in the south east. They are fitted with de-icer modules and apply de-icing fluid where required
http://en.wikipedia.org/wiki/British_Rail_MPV
8) Hired in by Network Rail - There are also electric locomotives stabled at locations around the country to act as over head line Ice breakers. This year there are two ( a class 86 & class 87) ready at Carlisle to make light engine runs up and down the WCML , mainly at night, to ensure that ice does not form on the overhead power lines. Here is a picture:
http://www.flickr.com/photos/darlo2009/8319952004/in/photostream
9) TOC - I should also mention "ghost trains" or empty trains running around the network to prevent ice and snow forming on the track or OHLE. I know FCC have been running some on the Bedford route over the last few nights.
10) TOC - Some trains in the south east have been fitted with de icing gear to help spread de icing fluid over a larger area than can be covered by the Network Rail trains.
The scot rail website referred to above has some good pictures on the first 4 items.
