The rules on bringing food into the UK from outside the European Union, apply to all food, whether it was bought from a shop (including at an airport), was home made or grown/produced at home. Different rules apply for different products:

Imports database - Search to find out what food you can bring into the UK.
Personal imports of animal products (51 KB)
Personal imports of plants and plant produce and products (113 KB)
Products of animal origin - List of countries detailing personal imports (51 KB) 
Bringing food products into the UK (260KB)
Bringing fruit, vegetable and plant products into the UK (310KB)