Ok, I'm not entirely sure what you want to know? How to do it or just recommendations for a specific light?
You want a rope light, but switched from a regular light switch? Sure. Pick the light you want, I'd suggest something like an LED strip light kit, most are low voltage anyway. You could use a rope light if you prefer.
You will need to run some mains cables no-matter how you do it. You COULD connect into the light circuit, but I would not advise connecting it directly. Instead install an FCU somewhere, with a 3A fuse, and link the rope light to that. You could even install a regular socket, if the light has a standard plug with a fuse. If using an AC adapter, you'll need an FCU, AND a socket to accept the adaptor. You can simply link the light-switch into the FCU.
I should probably add before you start going into this, you can buy RGB strip light kits that use a remote to switch on/off & change colour (you can just have white light if you prefer). This might be an easier option.
Lots of these available on eBay.
Thanks for the advise dan, can I ask what a FCU is please ?
By the way I'm really enjoying your build thread
Sure. An FCU is a Fuse Connection Unit (sometimes called a Fused Spur), with a changeable fuse. You will have seen them near cooker-hoods etc. Since the lighting circuit will probably be a 5A fuse or 6A breaker, you will need the FCU to make it safer. You can also connect to the socket circuit the same way.
Now I normally support anyone willing to have a go and learn, but if you're not sure I'd recommend getting an electrician to do this part. Or install it yourself, but get someone with electrical knowledge to look it-over before connecting it up.
Thanks
can you give me an idea of the wiring for this ? I was planning to ride it in to a current light in the room i know longer wanted to use
If you mean you want to connect it into an existing ceiling-rose without running new wiring, I don't advise it. You could certainly link a new circuit into the loop of an older ceiling-rose.
If you're sacrificing an existing light all-together, you could link the power from the switched terminals in the ceiling-rose, but not via the pendant cable since that's not an appropriate cable. You would still need to install a new cable into an FCU somewhere, then into a new socket (if required). This would be a little easier since you already have the switch wiring in-place.
This is how you could link the light into an existing ceiling-rose:
This is unconventional, but it is safe.
Remember to swap the standard 13A fuse for a 3A, otherwise this is all for naught.
I still advise getting an electrician, so you know it's all kosher!