VAT for most work by contractors on houses is charged at the standard rate of 20%. There are however some exemptions. If you are renovating an empty house or flat that has not been lived in for two years, and you use a VAT-registered contractor you could be eligible for a reduced rate of 5% VAT. This means a potential saving on lots of your repairs costs.
Full details can be found at HMRC under the section Reduced-rating the renovation or alteration of empty residential premises
Your contractor needs to be able to show HM Revenue & Customs evidence that the property has been empty for two years. Assuming you are the person liable for council tax we can provide a letter documenting the last date of occupation of the property.