A bit of care needed with Michelwood - its in the hotel on the very left of the site - so in via the sharp left at end of slip and keep going straight until small road on the left where hotel is. I think if you accidentally go right, its going to commit you to the services and I don't think there is any return.
I've not used Michelwood southbound, but I cannot remember seeing any reference to there being superchargers there. As the superchargers are part of the hotel and that hotel is only northbound side, I think thats going to backup the northbound only. Its been a while since I visited, but you get 2 hours grace before needing to register at the hotel, but reception is right on top of the superchargers so would be foolish to not double check with reception if its no obvious.
If you do need the supercharger going southbound, I cannot recall it being a long distance to the next junction. Unofficially, there is also an entrance out of the hotel road avoiding the Motorway, but again, best to double check with hotel reception - I had no issues using it even though there are access only etc signs but I was at the time registered at the hotel - good location when visiting Bloodhound.