Theoretically each of you is allowed to bring back an unlimited quantity of tobacco products,
as long as they're for your personal use. (You're not allowed to sell them on to anyone else, or to receive anything in exchange for them, even if you make no profit on the deal).
HMRC officials won't normally challenge you about whether the products are for your personal use (unless there's a particular reason for them to be suspicious, such as the importation of several different brands) if you keep to their guideline maximum figures. For tobacco the 'guideline maximum' is 3Kg. For cigarettes the figure is 3200.
http://customs.hmrc.gov.uk/channelsPortalWebAp p/channelsPortalWebApp.portal?_nfpb=true&_page Label=pageTravel_ShowContent&id=HMCE_PROD_0102 21&propertyType=document
Chris