Look no further than The Old Grudge 
Full details in an earlier recruitment post here: [A/H][EU]<Deathwing> The Old Grudge, the guild for older players is recruiting for HC 10.1 content!
I should add that whilst that post is particularly about raiding we very much a mixed guild. So if you just want to level characters and chat with people we are a good fit.
Feel free to contact me on Discord for more info.
Discord: Ezzergeezer
Battletag: Ezzergeezer#2731