Changing a pendant for new downlights

[HawkEye244]

Hello chaps.
I am planning to DIY fit four new downlights in place of a bog standard pendant to the bedroom.

The cables currently up there are 1.5mm2 t & e.
Do I run the new downlights in 1.5mm or 1mm cable ? These are led 6w downlights.

There is insulation above and the installation instructions say that blanket insulation can be placed above. It is Rockwall insulation. However, what about junction boxes etc ? My understanding is that electrical wiring can sit either under or over insulation but not to be wedged in between ?

Many thanks.
Hawk

 

[flameport]

Usual to extend a circuit in the same size cable, but for a 6A lighting circuit, 1.0mm² is fine.

Insulation makes no difference to a domestic lighting circuit, as even 1.0mm² cable is grossly overrated for the load.

 

[HawkEye244]

I’m really overthinking this - but at the same time I want to get it right.
I’ve run two string lines from either corner of the room which matches up with the placement of the existing pendant. However, if I am to allow for the positioning of the joists above and enough distance between each downlight (minimum 1 meter) I am left with too narrow a gap between one wall and the downlights – approximately 70cm from the wall – whereas the other wall allows for a gap in excess of 1.2m. It seems like option 2 diagram is the best solution as this would shift the centre point to bring more balance, but is this a good idea?
I realise this is a very novice question and I have never done this before. I’ve another room to do so it would be good to get a really good handle of the process and perhaps if there are other much easier methods?
Many thanks