That’s a bit harsh GgW!!!
Ginnypig is not paying good money to learn to understand foreign accents!!
There is no reason not to expect clear instructions, during your flight instruction in fact, it's a must.
This simply highlights the problems that FTO's are having recruiting UK instructors at the moment...a huge problem especially when it comes to CPL and IR instructors.
You should have been given the controls on your trial flight and the school should have given your fist lesson their best shot if, they want you to continue.
You are absolutely correct to look elsewhere if you do not feel comfortable...it's your money and a lot of it.