I assume this is tobacco you have bought in another country. If you bought it in the EU the law is that you pay duty and taxes at the rate of that country and you can bring it in to the UK for your own personal use. It must not be for resale in the UK nor be used as payment.
"I bring duty paid (EU) / duty free (non-EU) cigarettes back into the country for my friends. Am I breaking the law?
Yes, unless they're a gift and the amount falls within customs guidelines. If you sell or take any kind of payment (monetary or otherwise) for any tobacco products that you bring into the UK then this is classed as 'commercial use' - and is breaking the law."
i dont have any to sell. I am part of a selling/buying group on FB and one of their rules is no selling tobacco. I would guess it's because of the duty issue, but i was the wondering if duty paid stuff could legally be sold in general