As a “pretty old instructor” who has been doing it off and on for 30 plus yeas, as well as assorted commercial
amd airline flying, I would say there is a fourth possibility which avtomaton has missed, namely that the instructor was giving you good advice in parts, but worded it very badly.
Every instructor should know that students progress at different rates. The easiest, generally, are youngsters spending mummy and daddies money who don’t have to think about anything else, and those that find it hardest are those in their forties plus who can fly because they finally have the money, but who have a lesson on Saturday morning, spend the rest of the weekend with the family, work hard all week without opening a flying book or thinking about aeroplanes, then come back the next Saturday and has to spend half the lesson revising what they did last week.
Maybe, once the dust has settled, try to have a non-confrontational chat with the instructor and see what he reccomends you need to practise, then find an experiemced PPL instructor who can take you up in an Arrow and allow you to do so, better to pay for aircraft hire and £20 an hour for a PPL instructor than £££whatevs per hour for a CPL instructor.
Also, try to put out of your head that a CPL course is x number of hours then you do the LST. Just like learning to drive, people learn at different rates, different people struggle with different parts of the course, and very few go through the whole syllabus without finding something which is harder for them.
Finally, if work means you might fall into the “one lesson each weekend problem student” class, is it possible work and financially for you to take every Friday off ( or every Monday) as part of annual holidays, so you can have a long weekend with three or four lessons and time spent at the flying club / school doing self study ground school and absorbing the ambience of Aviation ?