All travellers entering the UK from any EU country (with the exception of a few new member states in Eastern Europe) are theoretically entitled to bring back an unlimited quantity of alcohol and tobacco, as long as they are for
personal use. The definition of 'personal use' includes bona fide gifts to others but not items for which you'll receive any form of payment (even if that payment is only 'cost price').
HMRC issue guidelines to travellers as to the maximum quantities that they'll normally consider as meeting the 'personal use' rule, without asking any questions. These include 3200
and 3kg of tobacco:
http://customs.hmrc.gov.uk/channelsPortalWebAp p/channelsPortalWebApp.portal?_nfpb=true&_page Label=pageVAT_ShowContent&id=HMCE_PROD_010221& propertyType=document
Your principal problem, at 17years of age, (when entering the UK where it's illegal for you to purchase cigarettes) might be justifying 'personal use' for the cigarettes you intend to smoke yourself. If questioned about the tobacco, you'd have to make it clear that you intended to give it to your father as a present. If you stated that your father was going to pay you the cost price for it, you'd risk confiscation of the tobacco (or being required to pay excise duty, import duty and VAT on it).
However:
(i) the minimum age for importing 'duty free' tobacco products, from outside of the EU, remains at 17 years, not 18. It would therefore seem illogical for HMRC to apply a different age limit to imports of 'duty paid' goods from within the EU ; and
(ii) HMRC staff at airports aren't generally interested in imports of tobacco and alcohol from within the EU. The weight and space restrictions on air travellers means that th