I have found the website Internet Archive (https://archive.org/) very useful as well. They have tons of World War II Technical and Field Manuals in pdf format. It just takes some looking.
I'd also recommend the Combined Arms Research Library - Obsolete Military Manuals Click on the Field Manual link and it should pull up around 200 results. I think it has all the FMs published pertaining to the Infantry Regiment from 1941-45 and almost all the Armored Force manuals from 1942-45. I've not found a PDF version of FM 17-32 from November 1944, but do have a paper copy of the Nafziger reprint (anyone remember paper copies!). I must admit it's a heck of a lot easier to research US manuals than British ones, most US FMs are available as a download these days it seems. I'd like to find the reissues of FM101-10 myself, the June 1941 and a very post-war 1950s version are online but not the late 1943 issue. Gary