Jack always seems to want to do what I am doing which can be a bit frustrating.
I wait until his nap to do anything that I don't want him around for like making phone calls (he always wants to talk to whoever is on the phone) or use the computer.
I usually try and involve him in the task which can take a bit longer but is usually easier and it provides distraction for him. We have a front loader washing machine and he loves to pull the washing out and put it in the basket, and he often passes me the pegs. He stands on the stool when I am putting bread in the breadmaker and passes me the ingredients.
He loves Hi5 so I always put that on when I want to have a shower and I get some uninterrupted time!! It frustrates DH a bit on the weekend as I will just automatically say that I am off to have a shower and Jack jumps up on the couch and starts chanting "Hi5, Hi5..." so DH has to stop watching whatever he had on the TV
Maybe when you are changing Tane you could get Gabrielle to pass you the nappies or wipes or entertain Tane with a toy/book etc. Often I make a big deal about how mush of a help Jack is and that seems to make him happy.
Hope some of this helps