Hi Antonio
Well, there are three differentials in the UK, there is the diy market, the non approved market, and the approved market. Monitored systems in the UK that call the Police must be installed by the approved market and there are two inspectorates that can provide approval http://www.nsi.org.uk National security inspectorate and https://ssaib.org Something Security and inspectorate board.
Both sites have a list of companies that they provide approval for. It would be quite hard to nail down exactly how many non approved companies are out there I know of several in my town that have come and gone over the years. DIY well there is a strong market for DIY we daily get requests for help from people doing DIY on their alarms.
Most approved companies can do the majority of your list we certainly can, sadly there is not that much call for some of it