An excellent (and 100%) correct answer from Hawkwalk, which is confirmed by the HMRC website:
http://customs.hmrc.gov.uk/channelsPortalWebAp p/channelsPortalWebApp.portal?_nfpb=true&_page Label=pageTravel_InfoGuides&propertyType=docum ent&id=HMCE_PROD_010221
However, you should be aware that HMRC are entitled to challenge you about whether cigarette products are really for personal use even if you bring back no more than the 'guideline maximums'. In particular, bringing back both cigarettes and hand-rolling tobacco, or a mixture of different brands of cigarettes, might make them suspicious. If they don't believe that the cigarettes (and/or tobacco) are genuinely for personal use, they could confiscate the lot.
'Personal use' includes bona fide gifts to other people (where you receive nothing in return) but excludes any sales to others (even if you sell at cost price).
Chris