How to hide too much cable under a ceiling light rose

[SJD]

Unless the new light fitting is very small, this all ought to fit with the miniature Wagos. Obviously the connections all remade with excess cable trimmed off. How about a photo of the new light?

 

[Sty1990]

It’s plaster, the house is quite old.

 

[Sty1990]

Here’s the new light with measurements

 

[brianmoooore]

You say the bath is above this. If the bath is directly above, and the bath panel is removeable, then an access hole could be cut, as long as it doesn't affect the legs of the bath. The board removed doesn't have to be replaced flush with the floor. A larger piece of chipboard can be fixed over the top of the hole.
Beware of pipes when cutting.

 

[Sty1990]

We seem to have done everything with this house the wrong way round! The bathroom has only just gone in and it’s click together flooring that goes under the bath and is sealed in, that’s right above the light. It’s a retired electrician who is doing the lights as a favour so don’t want to start making it a hassle for him. I was really hoping for a pre-made box type solution to cover it up. It’s strange because the cables really won’t budge in or out.

 

[brianmoooore]

Is your retired electrician familiar with Wago boxes? It doesn't necessarily have to be just one - the second light circuit can have one of its own, and another for this light.
Get him to try to work out why the cables won't move. It's unlikely that they are all that tight.
You're not the first householder to do things the wrong way around. Buying a house, decorating right through, and then finding that they need a complete rewire is extremely common. Almost the norm.

 

[Sty1990]

I’ll ask him in work tomorrow and show him if he’s not. Thanks for much for all the advice, it’s really appreciated