Law / Do I set up Company in Poland or UK (to invoice my schools and students)? [11]

Hi all,

I am an English teacher and I have to be able to invoice my schools and students.
Which would be the better way to go in England or Poland? As i know the time scales in Poland and bureaucracy that it takes some time. But when declaring taxes - surely i wouldn't have that much to declare after converting pln to £ so my taxes would be less than what I'd be paying in Poland.

I'd be interested to hear what people think of my ideas and to give some guidance /advice.
Thanks in advance :)