This link takes you to the relevant pages of the government website. however the main points are as follows:
It is illegal to:
sell a knife to anyone under 18 (16 to 18 year olds in Scotland can buy cutlery and kitchen knives) unless it’s a knife with a folding blade 3 inches long (7.62cm) or less
carry a knife in public without good reason - unless it’s a knife with a folding, non-lockable, blade 3 inches long (7.62cm) or less
carry, buy or sell any type of banned knife
use any knife in a threatening way (even a legal knife)
By enquiring about purchasing my knives you are agreeing to the fact that you are over 18.