A cold winter will cost you a fortune if using electrical heat. The only people i know that would choose electric radiators are landlords because they are paying for the install (cheap) but not the bills (expensive).
I would stick with the gas if i were you. Get a quotation from a local (recommended if possible) RGI heating installer. The existing boiler might be ok. If you need to replace, ask them about a Combi boiler as they give instant hot water (good for summer when heating won't be on) & you don't take up space with a traditional cylinder in a hot press.
How old and in what condition is your wiring? You'd be doubling the cost of your project but if you need a re-wire anytime soon (in the next 10yrs), there'll never be a better time than when your heating installer is there lifting the same floors, drilling through joists, you have furniture moved out, etc. If you need to touch up plastering/painting afterwards, you're only doing this once too.
How well insulated is the house? A lovely new high efficiency boiler will be of little benefit if it's just efficiently producing heat that is flying through you walls rather than heating the space as intended. For me, insulation is Priority #1.