It appears that this is a Tesco-exclusive deal - Kitchen Garden, April issue, comes with 5 packets of Mr Fothergills seeds:
Basil Sweet Genovese
Lettuce Webbs Wonderful
Courgette All Green Bush
Carrot Chantenay Red Cored 2
Beetroot Boltardy
Mind you, practically every gardening magazine on the shelves seems to have free seeds at the moment, so they face some competition!