Moving Light Switch

I would like to move a 2 gang light switch, I only need to move it by 30 cm.

Is it possible and allowed under the regulations to:
remove switch from wall
Chase out across 30 cm to its new position and fit a dry lining box
Put a 4 way 20amp junction box in the old switch box and run the connected cables in mini trunk in the chased area and fit the new switch.

The JB will then be covered by a blanking plate and the fridge will cover it.

Other this i will have to remove floor boards upstairs and jump that across and rechase downwards which will mean hitting a lintel above the door way

Yes, that is acceptable.

You could use strip connectors instead of a junction box at the old switch position behind the blank plate.

Make sure the old box remains earthed (assuming it is a flush metal type)

Thanks, I will use a strip then, steel back box will remain earthed.