the charge would be the difference in duty paid. Plus a possible fine and whenever you go through a UK airport you will probably get pulled aside as they keep note of offenders

You'll get charged as a minimum the VAT at the rate that would be levied here but on alcohol and tobacco you'll also be charged the full excise duty that would be levied here and not just the difference between any duty already paid in the country of purchase. Hence that 'bargain' will probably end up costing you more than you'd have paid at your local supermarket. Plus as Neilthebeaver says - you could still be fined on top of that. This is why most people who get caught trying to bring in more than their allowance just surrender their 'contraband' and have it confiscated - money down the drain if that happens. And whether you opt to pay the duty or to have it confiscated, you can expect to be pulled over whenever you go through Customs in future.

And don't forget, there is actually a good chance of being caught because the reason there are so often delays on being able to collect your bags from return flights from Tenerife is that Customs regularly x-ray all returning baggage on randomly selected flights specifically looking for alcohol and tobacco. People being pulled over on return from Tenerife aren't 'unlucky' - they're being caught bang to rights and the Customs only pulling over those people they already know have too much alcohol and/or tobacco in their cases

SM

It all depends on your attitude to risk. I brought 1000 cigs back betweeen 2 people, got caught and had them confiscated. I have gone slightly over the limit since then but had never been targeted.

you can expect to be pulled over whenever you go through Customs in future

Not quite true, daughter worked at the airport, and was told that this is very hard to do. They just scan cases and know the ones that have a lot of cigs in, which is why i have 3 packets in my suitcase and 7 in my handluggage, which is with me all the time.

i admit that yes i bring back more than i'm allowed, as do me hubby and our 12 friends that are usually with us.

We hubby and i have been pulled once and we had 20 packs, we just surrended them, and that was it. yes cash lost etc etc, but that is once in over 10 years of visiting sometimes twice a year.

Since then i've again brought back 10 packs each visit and never been pulled,

but i take a chance and it's one i don't mind paying.

When a friend of ours got pulled a few years ago, he asked what happens, and was told that on your 3rd pull you are taken to court. This was his 1st offence.
he said to the customs lady, oh so i have one more chance to take, and gave her a wink, she was doing her best not to smile at him.