The North isn't part of the EU as its an unrecognised "country" so EU allowances don't come in to it (If I understand your question, you want to fly into the North but nip over to get tabacco in the South and then fly home from the north again ?)

Provided you have receipts/proof they were bought in the EU there isn't a problem with HM Customs, so, EU allowances do indeed come into it. The issue is whether I would have a problem with the Turkish Cypriot authorities when I nip back from my brief shopping trip. From what I can gather, the said people are shall we say more amicable than their counterparts, if travelling with shopping in the opposite direction however, I seek a definitive answer. If it is going to be an issue with them, I will simply fly to Larnaca & very briefly stop to buy them on my return to the airport.

Certainly, doing the shopping trip the opposite way round would be a problem as the Cypriot Customs do check your bags at the exit checkpoint from North to South. They are particularly looking for cigarettes and alcohol.

Now, going from Ledra street into the North from the South checkpoint - I have not seen the same happening but of course, nothing is guaranteed.

I don't see it being a real issue to the North though, if you're bringing stuff in...