Gentleman Jim

Hi there and good luck with the tiling.
I made the same choice and gave up full time teaching to "go it alone" tiling. I now tile for three days and teach for two. What I would say is that folks are interested in what you do the rest of the time and how long have you been tiling. It's almost as if they think you can't do a good job unless you've been doing it for ever.
My tip to you is be honest at the outset and tell them you may not be the fastest in the world but you work clean, you work accurately and that you respect them and theirs!
Let us know how it goes.
Regards
Jim