Been using CTEK (and others) for years so here's my findings...
The older CTEK chargers and Lidl chargers don't restart automatically if the power source is disturbed so you will be required to reset them before they charge again
Don't leave the charger on your battery permanently as it will eventually destroy the cells. It takes a couple of years to do this and the battery will require to be replaced
CTEK housing is waterproof but make sure you use a minimum IP65 waterproof connection at any mains joints if you are using outdoors. 240v gives the human body one heck of a jolt and possible death...
Best to connect the CTEK and top up the battery once a week then remove the CTEK