DIY Doctor UK DIY Forums

My partner and I have recently put in an offer on a house (which we both love), but a basic valuation has highlighted that the polystyrene lining to roof void is considered to be a fire hazard and that it will result in 'sweating' to the sarking felt (probably resulting in subsequent deterioration). As the house was built in the late 60s we had hoped not to have a more thorough survey carried out as funds are very low. Does anyone have any ideas about the potential problems of polystyrene roof linings? How difficult/costly is this to remedy if we DIY?