There are many different issues to take into consideration when importing foodstuffs from abroad, depending on the type of food you are considering importing.
A good starting point is the Food Standards Agency's import page.
If you are new to importing food for commercial purposes, then you may find it helpful to contact the Department for Business and Trade.
They can advise you about trade procedures and documentation that you might need to comply with to import food into the UK. They can also advise you about trade concerns or issues, before you arrange for the food to be imported.
If you want to import foods that have an animal content you need to contact the port health authority for the relevant point of entry into the country - this might be an airport or ferry port.
These foods include fresh meat, meat products like salamis and sausages, poultry, fish, shellfish, eggs, honey and dairy products.