When I took ds to nursery for settling in sessions I tried to just be around, and let the staff pull him in to the activities they had set up with the other kids. Didn't take long for him to get interested!
I have worked since he was nine months so have needed childcare (previously he was with a childminder) but even without needing it I can see the good that it has done for my kid. More sociable, loves to share and take turns, exposure to different people and activities than he's had with me. Now he's at school he is in after school club a couple of days a week and it has had a huge effect on him fitting in to the school as a whole - he has kids older than him come up outside of school and greet him, hug him, want to play with him etc. So if I were to stop working now I'd find a way for him to still get to 'club'!