Are these benefits in kind taxable even at Christmas?

Variations on the following enquiry may appear on business and tax forums at this time of year:

I am becoming increasingly concerned about my potential liability to UK taxes. I am non-domiciled and non-resident (I think) in the UK – no permanent home here – but each year I work temporarily in the UK for a short period. 

The work is unpaid, but I do receive millions of unsolicited (but habitual) benefits in kind such as glasses of port, mince pies and the like. I am becoming concerned that I have not declared these to HMRC in the past.  The aggregate value of these gifts and benefits would be substantial but I have no idea how to value them all. Should I have done so and how would the value of is there an annual tax liability to be paid on these gifts and benefits?  

If I am subject to tax then I would want to offset my travel expenses and the cost of my vehicle and support staff - none of whom are on my payroll. Can I also offset the cost of customer gifts? (Few of them are food and drink but none contain my business logo as such). 

I like to think I'm being nice, but am I naughty? Do I need tax advice or can I safely continue to ignore my self assessment tax filing obligations?  

The usual pseudonym used by the author is "S. Claus". I wonder........