It can be a very varied and interesting career. If you already have a degree and experience then you wouldn't need much training.
ATCE is a catch all term for any one in enginneering. Generally there are two groups - service delivery - who work shifts and perform hands on engineering support for the ATC service. There are also the day job engineers who develop, support and test ATC systems.
It is a job for the flexible. I am a software engineer and as well as software design, development and test I have been involved in project planning, safety case writing, requirements gathering and analysis and on one occasion when I suggested trying my hand at Project Management I ended up running a project to soundproof the roof of an Ops room.
Generally it is well paid, holidays are good and once you learn to ignore the ATCOs it is excellent. Lots of chances to try other things, and no need to go into management if you don't want to.
I have been in NATS 20 years now and the people make it a great place to work. Most days I come to work with a plan of what to do and sometimes it even gets started.
Check your PMs for more info.