Home Information Packs are now compulsory for all houses being "marketed" through estate agents, newspaper advertisements, internet sites, so you could check through your estate agent what's required and start pulling the information together. Interestingly, HIP's are not required if the sale is made privately, between friends, relatives or if you are approached by somebody wanting to buy the property. If you Google "Home Information Packs, the government webtsite can give more info.