Sorry to interupt the dump on ppl's party.
Weight and balance, aircraft performance and safe operation (avoiding downwind landings when heavy) are a basic skill,
Any instructor would hammer this In and it is an extremely basic part of flight planning.
Stupidity is not limited to ppl's it is frequently shown by professional pilots also.
With 80-odd hours and only flying 1 hour in 3 months you can only expect a problem. There is no way to remain current like that. Those hours should be spent flying dual to reinforce the skills until such a time the pilot is flying often enough to be safe.
What are UK regs about currency? X number of hours and takeoff/landings?
A system can't route out stupidity nor can the instructor be responsible for what a pilot does or doesn't do after training.