If you just need to power a light that's normally intended for a permanent installation, there's not much too it.
For ease of use, I'd just recommend some wire-nuts:
And a cut-up three-prong extension cord.
The actual wiring depends a lot on where you are located. I can tell you the color-coding for USA wiring off the top of my head, but I don't know UK wiring codes.
What I can say is that the ground connection is almost universally green, and should always be connected.
I don't even know if wire-nuts are available in europe. I know that I have seen some posts on the Electrical Engineering stack-exchange indicating they're not really available there.
Wire-nuts are a nice way for joining wiring safely for either temporary exposed wiring (like you're doing), or permanent wiring if it's contained in an enclosure. They're nice because they're fairly safe, and easily removable/reuseable.
The nice thing about just chopping up an extension cord as a power-source is that you can be absolutely sure the system is safe by just unplugging the cord.
The most important thing I can think of is to be careful. Always be sure everything is unplugged before working on the wiring. A non-contact voltage detector is a cheap ($20-$50) safety precaution, and could save your life.