Thank you for the bump and the replies.
Apparently she has been referred, but it's all a bit vague (they may reject you, you should hear something within 18 weeks) and also when I spoke to the HV initially, I was not seriously thinking that autism was a possibility.
She does babble, sort of like singing to herself, and does like saying rorororo if I sing row, row, row your boat.
I don't think I've seen her point. If she sees something exciting she just kicks a lot and makes excited noises. She also giggles randomly, or so it seems. She occasionally claps or waves, but fairly half-heartedly. She will do things like come to me so I can take her downstairs to eat or for a walk, but she always looks like she's on automatic pilot. In the same way she sometimes bites me, but not in an angry way, but just because my shoulder was there, so why not!
I have done the MCHAT for her, and it comes out as high risk.
Physically, well she walked at 13 months, which seems pretty reasonable from what I can tell. She is still clumsy, but that may be just being a toddler; she runs about the room crashing into things, but this doesn't seem to really upset her. I don't recall any favouring of one side over the other.
Her playing usually involves throwing balls or play food into a container, putting shapes into shape sorter lid, she can be encouraged to build a tower from stacking cups, stroking the "touchy" bits in books (generally upside-down!). She sometimes plays with her sister, chasing games, but she gets upset if DTD1 closes doors when she wants them open etc.
Eating, she can use a spoon, but always tips it upside-down just before putting it into her mouth. Similarly, she turns beakers so that the straw etc is at the top. I don't think she has any specific food issues. She eats less than her sister as a rule, but not so much that I worry, and in fact has recently overtaken her in weight (she was already slightly taller).
Hmmm, that's got quite long! Thank you again for all the replies, and I will see what I can find out about the referral, and also put something on the SEN board.