Luckily I was able to access your site, so I was able to get some more details for you:
Can you contact your hosting provider and explain to them that we are unable to access your blog via cURL, which is needed in order to use Jetpack on your site.
You can let them know we tested the following:
1. Check for access to xmlrpc.php via browser:
That test returned "XML-RPC server accepts POST requests only." which is a valid result.
2. Check for access via cURL by running the following command from the command prompt:
curl -i -H 'Content-Type: text/xml' --data '<?xml version="1.0&"?><methodCall><methodName>demo.sayHello</methodName><params></params></methodCall>' 'http://jumpaccountancy.co.uk/xmlrpc.php'
The cURL test returned an invalid result, which includes the full source of your site (too long to post here)
Please provide the information above to your hosting provider so that they can correct the server settings to allow cURL access.
I also noticed that you are using WordPress 3.4.2, and not the most recent version, 3.6. As noted on the plugin page, Jetpack only officially supports version 3.5 and up now:
Updating your WordPress might even fix the xmlrpc.php error I mention above, so I strongly sugest you try that.
You are also using a very old version of Jetpack, 2.0.4: http://jumpaccountancy.co.uk/wordpress/wp-content/plugins/jetpack/readme.txt
You should update to the latest version, which fixes many bugs and adds new features.
Until you update both WordPress and Jetpack, you will continue to have problems with Publicize.