Changing Sprockets from 13/49 to 14/52

I think that putting a smaller sprocket on the front like a 12, would put more pressure on the chain. Probably because it has to turn on a smaller diameter. Id say the wear on the chain would be speeded up leading to the sprockets wearing out quicker. Don't know if it affects the load on the engine or not. Im guessing it wouldn't if the ratios were virtually the same

UK is correct.
Just make sure everything will clear when you go bigger, chain guide, etc.