Hi Marie,
Re mains electricity, have you spoken to the ESB about future plans to 'electrify' the area you're talking about? I have no idea as to feasibility, but would the fact that you say there is a phone line in the cottage not mean that it is possible to also get mains elec. put out there? Maybe contact a local T.D. and ask them to enquire of the ESB on your behalf? Would make all the above issues/most of them disappear!
On a related issue, don't forget if you're getting work done on the place i.e. bathroom put in, concrete being mixed etc., your builders/plumbers etc. are going to need a reliable and heavy-duty power supply.