Lets clear a few things up
Power line bourne disturbances are a completely separate issue to high current requirements, and surge protectors arn't magic pixie dust that eliminate overloading issues.
Now, I've looked into the wattage requiements of these light boxes for you, and most take sub 300w (about the same a computer and monitor), it really isn't a signifcant amount of power at all
Buildings such as halls of resistance have to limit the amount of high power appliances that can be used (such as kettles, toasters, space heaters, etc), because the installation in the building wouldn't be designed with loading that heavy.
But one 300w lamp, I can't see it being a problem at all, just make sure it (and all your other appliances) have been tested by a PAT guy as its quite likely they will insist on that (buy they might have someone who can do it in-house)
Take it from a trainne sparky, I can't see it being an issue at all
, its one SAD lamp, not a rig of threatre lamps, or a heap of kettles :P