"I supply and fit suspended ceilings and light fittings."
Perfect.
You say your clientèle will be businesses, shops, schools, surgery's, hospitals, sports facilities etc etc. Might you also be selling to shop-fitters, or people having shops fitted? If so, you need to think clearly about what you offer to each of those very different kinds of customers, then use your design and communication skills to craft messages to meet their needs. Think less about 'what I offer', and more about what they need - then mould your 'offer message' to their needs. (My guess is, eg, that whereas a local shop might go direct to you - to get a good price for 'that bit' - a school or hospital would be more likely to want to just use one contractor to refurbish a ward or eight classrooms, so if you fit into that picture, it would be as a sub-contractor to a main shop-fitter type company.)
What, in each case, is the message? And what's the medium? As has been said above, you'd do well to get at least some kind of a website together, even if it's pretty basic, along with business cards you can give to people, along with 'check out my website'. It doesn't have to be big or fancy, just enough so that when people take a quick look (which is all 9/10 will bother with/have time for), the impression they get is: 'well, he looks kosher'. My wife did some poking around recently and came up with these people -
http://www.create.net - have to say, I found the software pretty intuitive and easy to use, and the results look good.
I'd guess that when it comes to shop-fitters, you might actually find it worth phoning around, using Thomson or yellow pages or something. My guess would be that those kinds of businesses are often run by people who like to do things on the phone/in person, rather than going by flyers or whatever. Nine out of the first ten will probably say no, but one will want to meet you, and once you get started, you're in business.
Don't get discouraged. Getting started is the hardest by far. But once you get off the ground, if you do good work and don't muck people about, more work will follow.