Quiet baby concerns... anyone else?

My son turns 6 months on Saturday and isn’t really taking (obviously not actual talking but babbling etc.).

He doesn’t repeat sounds. He mostly makes squeals, sighs etc. The sounds he does make are pretty basic - Ga’s, ahh’s, err - that kind of thing. I thought a heard a ‘ma ma’ a week or two ago but haven’t heard anything like it since. I do talk to him and sometimes he looks/listens but most of the time won’t and barely ever responds. We read and sing nursery rhymes everyday.

I’m not concerned about any other areas as he’s physically very active and has even started ‘walking’ when his hands are held. He can reach for objects and bring to the mouth, sits up unsupported for a few seconds. He’s generally a happy baby and smiles and laughs a lot.

Is anyone else experiencing anything similar? Or does anyone have any advice? Tips to get him talking? Because I of course googled it (🙄) and that suggested autism!

Before anyone tells me to see our paediatrician, were from the U.K. so don’t have one. I could speak with a health visitor but have been told they’re unlikely to do anything because he’s still young.