would you recommend that book for learning regular expressions as a non CS guy?

Absolutely, it's an excellent book which I highly recommend.

The latest edition (3rd) is almost 20 years old, but I don't think regex has actually changed substantially since then so it should still be very useful. (I read the 2nd edition cover-to-cover and enjoyed it enough that I bought the 3rd when it was released 😀)

If you're going to buy a physical copy from amazon you should use the author's link here to give him slightly more money for it. But if you just want a PDF I see one is available here.