An Introduction to Gödel’s Theorems was first published in 2007 with the second edition appearing in 2013. A corrected version of the second edition is now available as a freely downloadable PDF. (The current version of this PDF is dated August 2020.)
Many people, however, prefer if possible to work from a physical book. So you can also get a print-on-demand copy of this version as a very inexpensive large format book from Amazon. US link; UK link. Find on your local Amazon by using the ASIN identifier B08GB4BDPG in their search field. (You don’t get the original pretty cover; but the quality of the printing and paper is very acceptable, especially given the low price.) Note that since this reprint isn’t coming from a publisher with a marketing department, you will need to ask your university librarian to order a printed copy for the library.
The book previously appeared in the series, ‘Cambridge Introductions to Philosophy’ from CUP. But don’t let that mislead you! IGT is actually a fairly techie logic book, originally intended for advanced philosophy undergraduates and postgraduates. It is quite long (388 pp.) and is full of theorems — so many mathematics students should find it useful too. Still, it does aim to give a relatively relaxed and approachable exposition of the technicalities around and about the incompleteness theorems, and it does also provide a modest amount of more philosophical commentary on the interpretation and significance of the theorems.