The salary depends on a number of factors. Once you're a fully licenced ATCO (about three years after you begin training) you earn about £40-50k depending on the pay band of your unit (Swanwick and Heathrow are both the top band). After this I believe there is a payscale you work your way up each year of service for about 15 years, you can also work your way up it faster by taking on additional roles (OJTI, watch manager etc). According to the ATCO careers website you can end up on over £90K at Swanwick.