You will have to join the IET or another institution in order to apply for ICT Tech. It is not a qualification per se more a mark of professional status, in the same vein as Incorporated Engineer, Engineering Technician and Chartered Engineer.
IT/ICT apprentices can be fast tracked to ICT Tech and TMIET, I'd contact a learning advisor (use the details on the IET site) and let them advise you. A copy of your skills, experience and qualifications will let them best advise you.
Hope that helps mate. Once you have ICT Tech,I think you can apply for a City & Guilds Licentiateship as well.
MP