If there is anything available it will fall under the Warm Front scheme - information about which you can find here.
http://www.direct.gov...rgygrants/DG_10018661
Warm Front applies in England - similar schemes under different guises appear in the 'provinces'.
However I think it unlikely to change your CH method under this scheme because it is intended for those without a CH scheme - and Economy 7 counts as CH. You might however be able to obtain a grant for a decent amount of insulation in the roof space.
It is impossible to obtain the cost of installing the gas main to the property via Warm Front.
Hope that helps, BM. Aged 58 1/4