James
Mine is about £40 a month. Last year I used 4.5 MWh and the combined cost was for both units, meter rental and VAT was a shade over 10p/kWh. Think I should use less this year as I have more insulation and I will get the MVHR sorted out as well.
Posted it up on a thread somewhere but can't remember which one now.

I think the difference between night storage space heating and gas space heating is the nature of use. With Night stores, they are exactly that, so you over heat at night and rely on the temperature decay to still keep the place warm till 11PM.
Possibly not a lot of difference in running costs between gas and water heating , though a very different CO2 foot print.
If I could put 4.5 kWp of PV on my place, stored most as heat and with a bit in batteries (about 4-5 kWh), I could probably manage to be theoretically off grid. Winter would be a struggle as I use up to 25 kWh/day and I would have more than I know what to do with in summer (electric car maybe). Would allow me to use electric resistance fan heaters when they are needed though.
Trouble is I can only get 1.5 kWp on a WSW (the cloudy side) facing roof.

Wholesale natural gas prices in USA, source US EIA http://205.254.135.7/dnav/ng/hist/rngwhhda.htm

year , price $/Million BTU
2005 8.686
2006 6.731
2007 6.967
2008 8.863
2009 3.943
2010 4.370
2011 3.996

The natural gas price in US is now less than half what it was in mid-2000s, is now back to 1999 level. Dont know if this is the famous shale gas effect, or just supply/demand.

But if same happened here, expect cheaper heating, cheaper electricity, more consumption, accelerated switch fron coal to gas, return of heavy manufacturing industries that have gone abroad, difficulty getting renewables investment...? Good/bad?

Have seen estimates from between 15 years worth to 75 years worth, so rather a margin of error there. Have also seen estimated that Russia has enough gas to supply the EU, at today's consumption levels for between 150 years to 400 years.
We have signed a priority contract with Norway for the next ten years, so should not have to suffer delivery uncertainty, though price can fluctuate.
Trouble is when gas, or oil and coal for that matter, gets too cheap, it is not worth bring out the ground. Coal has not changed in price for 20 years, globally gas seems to be getting cheaper, oil seems to be happy at around $100/barrel.
I am not saying that we shoudl be burning these, far from it, what I will say is that RE has to compete with it. No amount of tinkering around the edges with subsidies will allow this at the present time, though a heavy emissions tax on fossil fuel would be a game changer, though I cannot see that happening at the moment. 30 Euro/tonne is not high enough.