simon/Prentice, got box - don't want to mess it up now....
Am I putting light in and out on circuit one side of box, and switch and lamp holder other side?
what terminals does the switch live/live go into??
It does not really matter providing you keep the blocks of the same type.
The technique of terminating the cables, will be to strip a little more of then you would normal expect, about 15mm of bare copper.
Then using a flat headed screwdriver press the head of the connector down and push the cable in, so no exposed copper, release head and check cable has gripped.
You will also need to nip a bit of the cable entry knock-outs off, normally just the bottom knock-out at cable grips is enough.