Classic Back on the road

After a lot of work and tears, my RRC is back on the road. I had some welding done and MOT'd yesterday. New brake calipers, discs pads, air springs, dampers, anti roll bar links and bushes, suspensions bushers, engine top end rebuild, new radiator, new centre viscous coupling......etc etc
Still some problems of course so here goes........
I have no dashboard lights - no backlight to the speedo or any switches. Checked fuse and OK. Can the dimmer switch fail?
Driving home from the MOT, the car seems to have no power. I had foot to the floor going up hills. Any easy checks to start with?

Test the alternator, well done on all the other stuff

loss of power check fuel filter not blocked and the pump is working or any air leaks like the pipe to the vacuum servo or manifpld gasket