The UK Plugs and Sockets Regulations require appliances (rated under 13A) to be fitted with plugs by the manufacturers.
It was prompted by the number of accidents caused by people fitting their own plugs! There are exceptions, but you will find when you buy your appliances pretty well all, other than a high current hob, will be fitted with a moulded on plug. (Which brings another complication - if you cut that plug off, and the appliance is subsequently faulty, you may well get told that the warranty is void because you cut the plug off, which is rubbish, but still seems to be a prevalent thing)
These Regulations re–enact with modifications the provisions of the Plugs and Sockets etc. (Safety) Regulations 1987 (S.I. 1987/603) and make provision for the first time for certain requirements to be satisfied in relation to appliances.
www.legislation.gov.uk