I too take lessons in short spans of three to 6 months and then take a break to absorb all the "stuff" I've been given. Going back when I want to advance to a new level or take on a new technique. I think you will have some fun now that you've decided to give it another go. Most of what we do we don't need to know what the 5th degree of D phrygian is. I cheat and play parallel modes, using one box pattern. R-b2-b3-4-5-b6-b7 works with D phrygian, so the 5th is always in the same spot - in my box- waiting on me. Again you do not need all that stuff for 90% of what you will do. Well, you need to know some of it......... but, just a few rules as guidelines, the major scale box pattern and being able to count to eight will do most of what you will need.
Took up music when I retired in 2000. Banjo first, then rhythm guitar, electric guitar, some keyboard in the middle, more to help with the theory than the normal classical route taken by most piano players. Enjoy playing chord accompaniment on keys. Four string bass and now classical guitar - finger-picking keep me busy. I ate this elephant one bite at a time. Figured I had the rest of my life so just took it one step at a time and am enjoying the journey. I retired at 65, you do the math.
This site helped with the theory there are some great articles - upper left hand side of the screen. And here is a very good paper on theory.
http://www.billygreen.pwp.blueyonder...20Advanced.pdf First 20 pages covers the basics then the next 60 pages take you into intermediate and advanced. Print off the first 20 pages and read some each night. You'll know when to get into the other 60 pages.
For me the journey started 12 years ago and I've enjoyed the run. Been with two bands, one for over 10 years, and love jamming circles. Get involved with other musicians as soon as you can, jamming circles are the safest place you can be. No one cares if you make a mistake as long as you are trying. Here is what happens once a month in my home town.
http://mineolabuzz.com/BUZZ/TX/MINEO...n-main-street/ I'm the old guy, in the blue shirt and khakis, at the hole in the wall. See anyone getting on a newbie? Nope, everyone is having too much fun.
BTW welcome.