i noticed a setting in the forms.config file called 'workInNonJSMode' but setting it to true doesn't seem to have done anything.
I know that Episerver introduced support for forms working without js. I am not sure if you'd need to restart the site to have that working though, have you tried?
There is also a list of limitations, so might be that you find your answer here.
i have seen that blog post already and unfortunately it doesn't cover the issue i am experiencing. The limitations listed by lockevn are acceptable to the client as long as the forms work in a basic way.
I have fixed this issue now.
There is a slight difference between the js and non-js functionality that was causing the behaviour i described. basically, when its using js/ajax to post form data the post goes straight to the core controller identified in the forms.config but in non-js mode the post will first go to whatever controller is chosen by the template resolver. in my case the controller in question had one action on it that was set to only accept GET requests so episerver wasn't able to post to it. You don't have to manually validate or save any of the form data, as long as your controller action accepts posts then you should see the standard behaviour.