Depends. Personally, I wouldn’t (firstly, because I don’t really think it’s the right thing to do), unless it was a huge proportion of my business costs, in which case, I’d have accountants and legal eagles to fight it for me. I think that generally, HMRC don’t really like you claiming tax relief on them. As a small business, I tend not to draw attention to myself – it only encourages them to snoop around and then they won’t stop until they find something else.