Newbie who needs setup advice

This is going to be one of the issues with mass take up of EVs. Give someone a lead with a 3 pin plug on it and the majority of people are just going to plug it into the most convenient socket with no real thought about load or how that particular socket is fed.

The benefit of a new dedicated circuit, be it a EV specific wall box or a properly installed commando socket is it's a known quantity with limited points of failure. That socket in the corner of the lounge that the granny charger is plugged into before being dangled out the window is drawing a large continual current through a circuit with many points of possible failure. Is it a spur, and from where using what? If it's on the ring, when was the last time it was tested for continuity around said ring or is it pulling 10amp through one half of it, and what else is on that half?

Be careful with the "fit a commando socket" advice. Connecting an EVSE (irrespective of socket) to an existing RCD has a risk it will cause nuisance tripping. There is also a relatively rare risk the RCD could be blinded by a DC fault with the car resulting in injury in the event of a house fault. Another rare but significant risk is that a PME neural fault would result in a dangerous voltage between the car bodywork and true Earth. These rare risks are why the regulations and code of practice were updated and any EVSE used on a regular basis should be installed to comply with them for safety. Just because someone has used a portable EVSE (aka Granny)plugged into a ring for years with no issues, doesn't mean it is totally safe.

For now, I would certainly avoid plugging in the EVSE to garage. Perhaps get an electrician to check one of the other rings and use as a temporary measure with due diligence.