Your electricity board supplies electricity to inside your home. It goes though a large fuse usually 60 amps 80 amps or 100amps which is sealed with electricity board fuses and should never be tampered with.
The fuse is then wired to your meter which is also the property of your electricity board. This is then wired to your consumer unit (more commonly known as your fuse box) which contains all the fuses or circuit breakers. The number of these will vary depending on the size of your home.
Consumer units should be labeled so you can tell which fuse/ circuit breaker is part of what circuit. All the wiring for all your house starts at the consumer unit. Each fuse/circuit breaker protects the wiring for individual circuits. Usually you will have a lighting circuit on each floor as well as a "ring" circuit for your socket outlets. There will also be other circuits for things like immersion heaters, central heating, cookers, etc.