Extend wire behind light switch

[NotSoHandy999]

I am replacing a light switch.
The red/black wires in the wall are quite short, and the new switch has the connectors in a different spot to the old switch.
I can wire the switch fine but one of the wires is too short to let me attach the face plate to the wall with both screws. The wire is too short by 5mm or so.

Am I allowed to use a connector block/ screw terminal behind the switch to extend the wire?
If so, I will need to get some wire to use. What specification should I look for?
If not, what's the best way to extend the wire to give a little more slack?
Cheers

 

[EFLImpudence]

Am I allowed to use a connector block/ screw terminal behind the switch to extend the wire?

Yes, of course.

If so, I will need to get some wire to use. What specification should I look for?

Virtually anything will do.


If your new switch is metal, it will need connecting to the earth wire.

 

[Harry Bloomfield]

Made for the job red or maybe blue through crimps, used with a proper crimper might be best and take up least space. Red and black wires suggest it could be a very old installation, with no earthing of the lighting circuit.

 

[NotSoHandy999]

Thank you both - all working now