i would see the GP
was this not picked up at his 2 year check?
of course he MAY just be a late developer, but I personally would be concerned if, at nearly 3, a child was only saying 2 words.
I would see the HV. we had concerns about ds2 and his lack of speech and at 2.5 I saw the GP who told me she doesn't refer and that I need to see the HV.
that was crap, but tbh the Health Visitors DO normally do these kind of referrals and should have all the paperwork readily available and IME it was far easier going through them.
They will probably ask you lots of questions to try and establish whether it's a potential hearing/speech issue, or whether there is some other underlying problem then they will refer you for hearing tests, speech and language therapy and anything else they feel appropriate
waiting lists are often long for these things, so it's best you do this ASAP. If in the meantime he starts talking then all well and good, you haven't lost out at all and you can just cancel the appointments if you need to.
but better to be in the system just in case