I'm not sure if this will show up as it's marked as resolved, but here goes for now.. I think Jetpack is working now, pretty much, so thanks for that. Apart from...
when I browse to http://www.jockrock.org the regular (unresponsive) web main page is the one that shows up. If I click on a category then the Jetpack-powered page shows the 5 most recent posts or whatever, it's just the front / landing page not working.
I have set up a new landing page and blog page in Settings but can't find a way to 'force' the browser to show the Jetpack Mobile version. Is there something I'm doing wrong? I was hoping Jetpack's mobile version would get round any need to redesign but now I'm not sure....