Eletric Boilers

I installed one a few years ago and it was very easy to fit.

sponix

Yes, but they're expensive to run. You might also need an uprated electrical supply. Might be signifcantly cheaper to look at an off-peak storage system, if you really have to go electric.

You mean you a) have gas but can't get a boiler + installation cheaply, or b) you don't have gas and can't get it installed cheaply?

If (a) I suggest finding out how much it would cost to heat it with (i) peak-rate electricity (ii) off-peak electricity (iii) gas, and factor that into your choice of heating system

If (b) I guess you need to draught-proof and insulate all you can and then some, and then go for an electric system. I'd consider off-peak with a thermal store and radiators (or underfloor heating) rather than peak-rate or storage heaters.