Reddit mentions of The Clarke Tin Whistle: Deluxe Edition (Book & CD)

Seconded! I learned using the Clarke Tin Whistle Book and a whistle in the key of "C". There's a plethora of whistles available in various keys for under $20 each. See Dale Wisely's Chiff and Fipple Guide to Inexpensive Whistles for more information. A set of whistles in various keys, especially C, D, and E, will provide access to most of the comfortable "guitar" keys -- a D whistle can play easily in D, Bm, G, and Em with minimal cross-fingering. I have played Clarke's, Sweetone's, Generation's, Shaw's, and Susato's among others, and while all of them have their own character, I think I prefer the playability and tone of the Susato line best.

You're new to playing it, yeah? In which case, get what I list or other reputable brands (which I also list) in the same price range. If you really get into it, you can look at more expensive super-deluxe models later.

Just get a Clarke D whistle, they're @$10-15
https://www.amazon.com/Clarke-CWD-Celtic-Tin-Whistle/dp/B0002I8Y6W

Clarke's what I play on, they play fine. Any D whistle made by a reputable manufacturer (Generation, Feadog, etc) will do, though. Some play a bit easier than others though and you may find you have a preference.

Get the Clarke book too @$15
https://www.amazon.com/Clarke-Tin-Whistle-Deluxe-Book/dp/0962345679

There's also the Geraldine Cotter books and a few others which are quite good, but if it's just the one, I'd just get the Clarke, it's fine.