If the HV is so concerned, why hasn’t she referred him to speech therapy? Given the ridiculous waiting times, if she is concerned she should do this ASAP.
As a pp said, if you have speech therapy drop in sessions or groups at your children’s centre, you can access these for free and they can be helpful.
Other than that, things like making him ask for stuff, eg putting only a little bit of dinner on his plate, so he has to ask for more, putting toys out of reach, so he has to ask for them,etc. It’s helpful to narrate what he’s doing, eg ‘pouring tea’, ‘rolling car’, etc, so he connects sounds/words to objects/actions. Repeat back what he says, but adding one extra word will help him learn to speak in longer sentences, eg ‘rolling red car’, ‘Thomas rolling red car’ etc.
Having said all that, at not long turned 2, he doesn’t sound wildly delayed to me. Is he communicating in other ways, making eye contact, pointing etc?