The BMS is on the left side (driver side for non UK cars), it is visible also in older videos and in the new 40kWh dismount video made by EVs Enhanced. However none of those videos/pictures can you see such a device on the right side of the battery pack. Inside there is nothing just a vertical holder which holds the read battery line.
A fan would be good there to vent the hot air out from the battery pack in case the ambient air temp is lower than the inside temp of the battery pack. If you continuously remove the hot air, it will help to reduce the battery pack temperature to ambient temp in a short period of time (like 1-2 hours depending of the temp difference between pack & ambient air temp). Of course it is only working for milder climate, not for hot desert, however parking the car in a cool place (A/Ced garage, etc), could help to reduce the battery pack temperature. The problem is the condensation what you might get if you let outside air inside the battery pack...