Several years ago, when I first retired, I walked off a lot of weight. This is some of what I learned.
Absolutely, you need quality shoes, and should analyze your gait. There are a number of websites online that will help you do this. If you google up overpronation and underpronation you will find them. I found the websites more helpful than going to the running shoe stores, where the teenage clerks made quick judgments after I had walked only 12 feet or so.
I have been wearing Asics running shoes, and even though they are pricey my foot problems are gone. The website tells which shoes are helpful for which conditions. I bought some for my husband, after analyzing his gait by the wear of his decrepit old shoes, and his back pain was immediately gone.
Posture seems to be important for me, too. Don't just throw your shoulders back, as that can be unnatural. Think of your head being suspended by a string or whatever from above, and your posture should be correct.
When I first started walking I was swiveling my hips a bit in a girly way, and that made my joints sore. Be sure to keep your hips straight as you walk.
When I was heavy I found myself lumbering from side to side, which is bound to be hard on body joints somewhere. It might be a good idea to watch yourself walk in a full length mirror or store window, and make sure that you aren't doing this.
I also tried to keep my core muscles of my abdomen tight as I walked, too. It helped.
It really did help me to think about my gait when I walked - the things that I have mentioned. After awhile my mind would drift, but then I'd remember and do it again. Good habits take a bit of practice.
As far as your specific complaint goes, it wouldn't hurt to google it up and see what you can find as a corrective exercise. Years ago I had a knee area problem. I found a specific exercise in a magazine, and could actually feel something move back into place when I first did the exercise.
Good luck with your training, shadowfox, you will be amazed at how good you will start to feel! Let us know how you do in October.