When you say you're starting a company, do you mean you are simply going to be working for yourself as a one man band, or starting off with shopfront and staff ?
If you are basucally just going to be working for yourself as a one nam band, which is probably like the majority of people on here then in my view there isn't really any market research that you can do because it's not like you have invented any thing and need to gauge if there is much of a market out there for your new product, your simply offering a service that pleanty of other people are already offering.
Market research works by having people standing on the street, stopping people and asking "do you like to have your bathroom or kitchen tiled" that sort of thing which is kind of pointless, lol
Thing is you just need to let people know you are there, and thats just
standard advertising.
You can spend as much on advertising as you want obviously, from posting flyers through letter boxes, business cards in kitchen\
tile shops, other trademen like plumbers, paper adverts and all the way to TV and radio if you feel real flash
As for competitors, all you can do is phone other shops or tradesmenthat do the same work as you do and ask for rough labour costs and compare that to what you feel you would need to charge.
Suppliers ?, if you're just working from home by yourself then you just need trade accounts with a couple of
tile shops, just go in to them and ask what they need from you to open one, if it's for larger supplies if you have a shop then you need to get your materials from source which will be far cheeper when buying in bulk.
Sales forcast ?, impossible to say.
Contracts ?, contact building companies, local councils etc and simply ask whats needed to be on their contractors lists.
Sorry I can't be any more help.