we did makaton with our boy and it was amazing - really helped with his language development - his first words were all ones that he had signs for. Now his speech is improving, the signs are falling away, but he sometimes includes them for clarity. From our experience, I would definitely go down the signing route if you discover that your child ends up with speech delays or a speech condition.
We have just started our 2year 8 month old doing horse riding therapy and it's amaizng. I think your child would be too young, but it's worth contacting all the centres now as they have long waiting lists. Look on the RDA webiste. I think some do take younger kids in carriages to get the movement, but I'm not sure many do (maybe ask the Diamond Centre in Surrey about that).
We did portage for a while before our boy wen to nursery and it was very good.
Swimming therapy is good. I also got a lot of soft play equipment at home from Wesco (need to google it and order a brochure), which I think is helpful.
Lots of soft play - somewhere like gymboree I find great at encouraging movement in young children. Though you get to the difficult decisions on whether to keep your kid in the class with the younger children at their physical ability or have them around the same age. I used to find that difficult but possibly do a bit of both.
I don't think there is medical research yet supporting the horse riding therapy, but I think it's doing something for our boy, at the very least he's loving it!!
We looked into this primitive reflexes Occupational therapy thing, which I'll maybe go back to, but felt like we were overloading and I don't think that yet has medical research behind it too much yet either.
Good luck with it all.