However good you are at DIY you will be doing a job for the first time that someone else has spent a lifetime learning how to do properly.
You can always tell an amateur job from a professional one; and that’s the key; if you are going to Get Someone In make sure that someone is a professional.
When you want a professional tradesman check out their trade organisation; with tiling it’s The Tile Association. TTA checks out any tile retailer, fixer or tile fixing company wishing to join their ranks. It checks their experience, abilities, track record and financial health. Fixers have to provide customer references, and have their work checked out or be recommended by an existing fixer member.