I am an instructor so I may be able to help a little bit on this one. An AFR leaves a lot of discretion to the instructor as to the content, although there are certain things as per the MOS part 61 that must be covered. Given your time away from flying, this would be a case of investing a lot of time on the ground covering a lot of regulations etc, and just getting an idea of where you are.
As for the flying, it’s really about demonstrating you meet a particular standard. How long that takes is dependant on a lot of things. Personally I’m not a huge fan of taking AFR students on long navigation exercises, the days of the EFB have made Nav pretty easy. You would probably benefit from an hour or so of general handling, and you would be surprised how quickly the skills come back. Then I would suggest a mini Nav using an EFB to an uncontrolled aerodrome.
Its always hard hard to make a judgement call on what your looking at time wise with having the context of your prior experience etc, but at a guess I would say your probably looking at about 2 hours ground, maybe reduced to 1 if you did lots of study before, and about 2-2.5 hours flying. That’s all a guess though.