The prototype lasers are about 1 milliwatt. This is a class 1 laser (see https://en.wikipedia.org/wiki/Laser_safety).

Military systems use about 2 to 150 kW to knock out small targets like drones. That is 2 to 150 million times larger.

Blowing up Alderaan (assuming it is like Earth) takes about 2.49×10³² J. At these energies, you will need some good quality PPE (Personal Protection Equipment) so don't buy it from the people who supplied the UK government.