Hi Sergio,
I grateful to hear that your English is top notch and that you love our country! I also think it's brilliant that you want to have a career in British air traffic control! A controller at Heathrow can easily expect at least £100,000 (about €150,000) per year. As mentioned earlier, yes the workload is very great and it is strictly illegal to usually work anymore than 4 days per week, and each day you would only work for maybe 60mins at a time. You will need to obtain a PPL (Private Pilot's Licence) first because the theory is that you need to understand what it feels like to be a pilot who needs ATC coverage (in other words, you need to understand your clients' roles in flying and navigating their aircraft!).
I happen to really want to become an airline pilot, and so I am half-way to becoming a private pilot. I train in Gloucester, UK and it is a controlled airport, and so controllers need to be there at all times. I've been lucky enough to speak to the controllers because I once had a work experience week at the airport. Another good idea (although it may sound stupid) is to get into flight simulation (as in computer flight simulators). It's what got me hooked on aviation since the tender age of 9 and I am ALWAYS using Microsoft Flight Simulator 2004. I say this because this version has ATC on it and you can also fly online with hundreds of other virtual pilots and air traffic controllers and so you end up speaking to virtual controllers but who sound VERY VERY realistic and professional. I use a network called VATSIM for this experience and there is seriously nothing that gets you closer to real-life flying, except for the "REAL" thing! If you'd like anymore advice or information, just ask!