That should all change now that the UK government has published quite a lot of information and clarification online.
Don't Bring Me BackThe UK Border Agency publishes a leaflet about bringing fruit, vegetable and plant products into the UK that can be downloaded as a pdf document.
Personal Import Rules DatabaseEven more useful, and more comprehensive, the Personal Import Rules database provides detailed information, by country, on hundreds of food products (including animal products) you might bring into the UK in your luggage, or send there by ordering online.
The database also has information on weight limits. So, for example, if you bring honey in from most places it will be part of a 2 kilos (about four lbs) per person total allowance in combination with live bivalves, eggs and egg products, skinned frogs legs, reptile, insect and snail meat (yum). So if you can bear to leave the clams, boiled rattlesnake and chocolate covered ants behind, you could, in theory, bring in 2k of honey.
And you can bring a 20k (that's about 40 lbs) combination of fish and fishery products (from most places) that can include live lobsters. How you are supposed to keep 40lbs of live Maine lobster alive on a transatlantic flight is a good question - but I'm sure someone has the answer.
Don't Even Think About itMilk products from outside the EU are banned - so no powdered milk drinks from Australia or that nice hunk of Wisconsin Cheddar you were planning to brink Great Aunt Felicity. And potatoes or potato products from anywhere (including the EU), even canned, bottled or otherwise packaged, are strictly verboten.
To find out what you can or cannot bring, simply enter the country from which you (or the goods)are entering the UK into the search box; use the search categories to refine the food category and actual product, click the button and the information - including weight limits - pops on screen.
These are personal allowances for your own use. Officials are allowed to use their discretion about "reasonable" quantities (for personal use) of products that are not weight restricted from both EU and non-EU countries - bagels from New York, chocolates from Paris. Large amounts that could be for commercial use could be subject to health checks and other commercial regulations.