Temporary heating solution needed!

I wonder if you can me some advice. In April 2009 we purchased a single storey property of about 2500 ft set in a plot of 3.9 acres (of which 2 acres is paddock) in land designated as countryside. The property comprises of a 3 bedroom bungalow of 1600 ft of block construction and tiled roof and 900ft (designated as an annex) containing 2 bedrooms built in 1948 with additions in a mixture of prefabricated walls and block all of which are single skinned. It is our intention to knock down and rebuild to around 3000 ft over 2 storeys but due to finances and planning etc this will not happen for 3-4 years.

I would like some advise regarding my options in heating the property before we commence redeveloping as the larger (and better insulated) side of the house is currently heated by LPG gas boiler ( Potterton Kingfisher II ) serving 9 radiators and the older smaller side of the property being heated by oil fired boiler and 6 radiators on micro bore pipe (Boulter Boilers Camray II). During this winter we have had problems with the LPG boiler lighting and maintaining it’s pilot light despite 3 costly visits from different engineers the last of whom told us that parts are no longer obtainable for this. We have also found that the Oil tank is not correctly fixed resulting in suppliers being unable to supply more fuel oil until it is replaced on a new plinth at a cost in excess of £1000 overall.

Given that it is our intention to demolish and rebuild in 3 to 4 years we are loathed to either replace the LPG boiler or make expensive rectifications on the Oil Tank and plinth but can not go though the winter without heating of some sort particularly with 2 children. If we do need to replace the boiler how feasible is it to link the 2 radiator systems and would it be possible to re-use the new boiler in the redeveloped house when we go ahead bearing in mind we will be considering under floor heating and possibley ground source heat pumps etc on the new build?