Though Tenerife and the rest of the Canary Islands are part of
Spain, which is in the EU, the islands have their own autonomy and
this is shown in such things as duty-free allowances.
Unfortunately, you are still restricted to 200 cigarettes per
person in this regard.
UK Customs "guidelines" are 800 cigarettes - but this is not a
legal limit - the only legal limit is that you can bring ANY amount
provided they are for personal consumption