Hi
According to the Bible (lasors) the requirement is this:
5 hours night flying as Pilot of Aeroplanes,
comprising of at least 3 hours dual
instruction, including 1 hour cross-country
navigation. and 5 solo take-offs and 5 full-stop
landings.
More here:
http://www.caa.co.uk/docs/175/SECTION%20D.pdf
I gatehr from this that they require you to have this experience. Where you gain this isn't stated. They also don't state what signatures you need.
I would assume that your logbook would need to indicate this experience and naturally the 3 hours dual instruction should be signed by the instructor.
Hope this helps.