You may be eligible for VAT Relief on certain goods and services if you are disabled
(you may not have to pay the VAT).
For instance if you can't walk, you may not have to pay the VAT when you buy a wheelchair.
The following (RNIB) Website gives you a rough idea of the process.
Click 'here': RNIB: VAT relief ... for disabled people
There are several VAT Relief leaflets on the Customs and Excise website, here are two:
Click 'here': Notice 701/7 - VAT Reliefs for disabled people
Click 'here': Leaflet - FAQ: VAT for disabled people
and your supplier will need your Eligibility Declaration Form -
Click 'here' for: Sample Eligibility Declaration Form