Your instructor may want speeds in the 100 MPH range, so discuss with him first. In my training, I used 100-110 on the approach. You can practice a bit while VFR to figure out the RPMs. You'll want a target RPM to go to once setting up the approach. After the initial setup, you'll adjust the RPM a bit to keep your airspeed on the desired target or range.
Some will argue that the RV's are easier to keep on the GS at higher speeds and I would concur. However, I felt it was a better learning experience to do the approaches at the slower 100 MPH speed. It is more work to maintain the GS, but you are in training and should be striving for mastering the most challenging scenarios. It also takes out the drama of slowing down for landing. Your instructor is going to leave you under the hood until 200 AGL on most every approach and you don't want to then figure out how you're going to lose 50 mph and add flaps when 1 mile from the runway. Especially early in your training. Once you're more experienced, you will learn to slow down gradually down the GS or at certain AGL steps/points. But that is not something you want to add on to the pile during your early learning.
With an FP prop and low ceilings, you're going to spend some amount of time on the GS at 100 MPH, so might as well learn how to do it.
I got my rating in my 6 and really enjoyed it. I am sure you will as well.
Larry