LED strip lighting inside roof lantern

[Mr Chibs]

I have an led strip, mounted as notch suggests, although my roof is solid... it produces a nice bit of ambient light.

 

[SimonH2]

Thanks @Notch7. Regarding airflow, I am not sure if the roof construction will allow full airflow. Mushroom vents have been put into each of the corners on the roof. The builder says this is sufficient, and building control are not really interested if there is full air flow; they just 'tick the box' if ventilation, i.e. mushroom vents, has been installed.

That doesn't sound like much.

Yes, the idea is to have insulated boards as well on the lantern reveals to keep the heat within the room. My concern now is that with having downlighters along the main ceiling perimeter and punching a hole through the lantern reveal for the wiring of the LED strips, heat is going to get through to the cold deck and cause condensation. I just hope I am wrong.

Downlighters will be a problem. You are breaching two things - the vapour membrane and the insulation. Unless you are careful with luminaire choice and even more careful with fitting, then you will let moist air into the roof. This will cause condensation, especially around the luminaire where you've removed the insulation and thus let the cold down to the ceiling surface.
And that's apart from the fact that downlighters are the worst type of lighting you could fit - apart from none at all. They are, by design, really rubbish at providing the sort fo light you need in almost any room of the house, and especially a kitchen. If you want harsh light, that casts terrible shadows where you don't want them, lights up the floor rather than where you are working, creates bad reflections if something reflective is under it - then great, they fit that role. If you want good light, without the "little pools of light" effect, without the harsh shadows, that doesn't create glare off your glasses (I wear glasses), then don't fit downlighters. Strip lights - i.e. the good old fashioned flouro strip or an LED equivalent (or multiple surface mounted "bulkhead" fittings with diffusers), plus under-cupboard lighting for your worktops, is about the best you'll get for a kitchen.

I will talk to my builder to see what he thinks about the fitting for the LED strip lights. I have already floated the idea about the LED coving from Screwfix and he thinks that will be fine.

One thought that immediately comes to mind ...
If you have the LED strip (or any light source for that matter) shining across a surface then it will highlight every tiny imperfection (and spiders' webs, and holes where SWMBO thought it was a good idea to fix crimbo decorations with drawing pins, or ...). So if your plasterer isn't 100% perfect, then you'll see the details all the time the light is on. If you, for example, arranged for the light to shine across the lantern to the opposite wall, then it'll be more diffused - and because it's hitting the surface at a large angle, then it doesn't highlight the imperfections.
If you did decide to fit the LEDs shining across the lantern, there are profiles designed to fit flush, so you'd just see the plastic cover strip rather than a surface mounted "something".