Coop have very nice Thick Cut Seville Marmalade. They also have Lemon Curd, which is delicious (strawberry, lemon curd and butterzopf sandwiches, yum).

Migros online (leshop.ch) has a section on british foods - has things like smokey bacon crisps, crunchies (3 for 5.10), cadbury flakes, tetley tea bags etc

And I second the Lemon Curd in Coop being very good!

Marmite substitute? In the food hall downstairs in Coop on Bahnhofstr in Zürich (Coop St.Annahof), you can buy Marmite. Find where all the dried herbs are, the Marmite is there on the bottom shelf.

I found Quality Street in the Otto last week, if you don`t have an otto near you, i will be in Zurich for the fish and chips night i can bring some along if you let me know how many you want they cost 3.95frcs for 265g expiry date 24/06/09 so still good for christmas

Not quite local, but after a trip over the border last month I tried a Nurnbergwurst (not entirely sure of spelling), anyway, they are the closest, so far, to english sausages that I have found, very nice.

And I saw them in Migros (and bought obviously) a couple of weeks ago