Tiling is a good buisness to get into, but it wont happen over night, it takes around 3 years to get a buisness up and running properly, what you need to do is check out how many other tilers are in your area, ring them up and ask them what they charge a sq metre. if your in it just for the money your in the wrong game, you have to enjoy tiling, and have a flair for it. keep your overheads low, try and get some weekend work tiling before you decide to jack your job in, incase you dont like it, im not trying to put you off, i did a course two years ago and the first year was hard but its getting better and better now. good luck what ever road you decide to take.