1500kg would be legal but hopefully you can find combo that is a little lighter to give you some margin.
Braked trailers usually operate manually, when the car brakes the weight of the trailer pushing on the tow ball automatically applies the trailer brakes. The key to good towing is anticipation and gentle braking and acceleration.
One thing you may not be aware of, if you passed your driving test after 1st January 1997 you don't automatically have the right to tow up to the 8,250kg maximum which many people are now aware of. If you're pulled over by the police while towing, the first thing they will check is you authority to tow the weight you're towing. There have been a number of changes to the rules since then which you can find here: https://www.gov.uk/guidance/new-rules-for-towing-a-trailer-or-caravan-with-a-car-from-autumn-2021