With this number of faults, a power surge has most likely damaged other components too (magnetron) as well which could make this uneconomical to repair, the same model is going on ebay here for £260 still in a factory sealed box.
However in terms of sourcing spares, for your Panasonic microwave I would suggest you use a spares firm such as espares or partmaster.
The safety switch I assume is the door micro switch you are referring to, and can be found here for under £10.
The light suggested by espares is wrong you require the one which has two spade terminals rather than ES, and can be found here for £5
I assume the PCB you are referring to based on the P/N s the inverter which is around £110 from here.
Please let me know if you need anything clarified.
If you need further assistance please let me know.