It is illegal to manufacture spirits in the UK without a distiller's licence which is required under the provisions of section 12 of the Alcoholic Liquor Duties Act 1979 and this includes manufacture for "own/domestic use".
Public Notice 39 - "Spirits production in the UK" dated April 2010 provides further information about HM Revenue and Custom's requirements.
If you require further assistance then please contact the National Advice Service on Telephone 0845 010 9000 or www.hmrc.gov.uk. Where you can obtain or view public notice 39.
Please note the Still Sprits flavourings and yeast are legal as long as you DON'T distil to get the higher alcohol. As you are fermenting the yeast and using duty paid vodka to use with the flavourings