How do I find out if the wooden flooring under my carpets is in a good enough condition?

I live in a tenement flat, built c 1830, and would like to find out if the wooden flooring under my carpets is in a good enough condition for me to take the carpet up and get it all varnished. I have pulled the carpets up at the corners and found nice broad dark wood flooring, but I don't know how it is all over the floor and if it is worth my while pulling it up. Who does these sort of jobs and how much should I expect to pay to get the floors varnished, uming I can?