Actually, I call the cleaner Claire.

Just for you, I may call a till a POS device. (Point of sale apparently.)

The difference between may and might? According to the OED, they may (or might) be interchanged depending on context. Of course, you also need to add in the fact I may (or might) be typing conversationally, which means you have to factor in dialect.

Sorry, tell you what. I may (or might) start using the style guide I am forced to put up with when writing for publication. HMSO publications and Mudcat ramblings may (or might) be different but to an uneducated (or poorly trained) armchair socialist, they are near enough.