Think back to the day you pitched up to attempt the initial ATCO selection. Just after you presented your proof of Identity and before they let you anywhere near the selection process, you signed a little slip of paper.
remeber what you were signing??
ATCO is a mobile grade and NATS can post you to any unit in Great Britain (although not any UK unit).
You will all go where you are told to, or leave NATS' employment. Same deal as we had from LATCC to LACC.
Deal with it.