OK, I've just done a quick bit of reading of the legislation (disclaimer: I am not a solicitor, I know didly-squat, don't take what I say as fact )
Producing spirits by whatever means without the relevant licenses is illegal, personal use or not, and they are not easy to get: https://www.gov.uk/guidance/spirits-duty
Spirits means anything other than wines, beers and ciders produced solely by fermentation: http://www.legislation.gov.uk/ukpga/1979/4
So, we can ferment anything we like to make anything we like, but not then distil it, freeze it, or crack ethylene gas to make it into a spirit.
Boo, hiss!
Note that there are some additional bits about percentage alcohol in the fermented beverage, but not anything that's likely to be an issue as long as it is only fermented.
That's interesting Foxyrick. I remember a long time ago reading personal consumption was okay, and even remember on the news a few years ago of a guy trying to make vodka in his apartment and blew it up, but even on there they said he wouldn't be arrested as he was only making it for personal use.
Not that I rarely drink even wine nowadays. I'd like to try making an essential oil at some point, but I think it's going to need lots of whatever plant used.
I used to distill the tap water for my soap making too until a chap in the next town who owns a soap factory told me the local tap water was fine as it is yo use.