I've also been assessing my son's plugs in his room, he's got 4 in one extension but they're TV, Q box and games consoles which I'm sure use little power so should be safe (I hope)
No problem with putting low power items into an extension lead.
My son has a TV, Xbox, PS4 and a TP-Link Powerline into an extension lead. (Not coiled up)
If you are interested in seeing how much current an extension lead is using the you could get something like this..