You canom receive a zero-rate of VAT on the work if they install, extend or adapt your bathroom, washroom or lavatory. But the work must be necessary to suit your condition.
For the purposes of this relief, the following definitions apply:
The VAT is zero rated on the items you mentioned and if thesupply is made by the company doing the work they can zero rate the supply.
A written declaration from from you would be needed to show that you are entitled to VAT relief.
A sample eligibility declaration for you to complete is shown on the following HMRC page:
Your supplier will be able to explain to you the items and the services that will be covered by this.