I think, if I can be honest, you're aiming a bit higher than your capabilities.
I'd avoid contacting such contractors until you have the experience and knowledge to tender for such contracts. And of course the skills when it comes to keeping them.
The more companies you contact now, while you sound so inexperienced, the less you'll be able to contact when you do gain the experience you need as they'll already have you on file as a no-go.
The advice above is good but I think you might have better success working with an existing tiling contractors as one of their tilers rather than bidding yourself. They'd then take care of all the things mentioned above and just let you get on with the tiling work.