In general lighting and heating can be split into two groups, required for living, and decoration and ambience. There are strict rules for required for living, the amount of lumen per watt for lights, and energy rating for heating, this is why we no longer have tungsten lamps or open hearth fires, as main lighting or heating, however we can still use log burners and silly lights for decoration and ambience.
The main point is any light or fire which is for decoration and ambience needs to be installed in such a way its use is optional, so fire is not required to be lit for central heating to work, and standard lights can be used without having to switch on lights for decoration.
So two switches on the wall one for standard lights and one for decoration is OK, single switch working both, not, unless there is something like a pull cord to switch off the decoration.
Today we should expect all new lights to give 50 lumen per watt, or more, old lights OK it is not retrospective, but new lights should be better than 50 lumen per watt.
However as yet there is no law to say all that, it is just common sense, so if you want to fit 13A sockets to lighting circuits or fit lights at 25 lumen per watt you still can, and that is the way it should be.
What you do want however with decoration is if an error is made or something fails it should only take out the decorative lamps not the main lights. As to if a 1A fuse will rupture before a 6A MCB not sure, but if fitted then you have watched your back, i.e. if the power supply fails short circuit and the fuse does not rupture and after being plunged into darkness the occupant is injured, you can stand up with hand on bible and say you took all reasonable care.