Ok, thanks to a fast and helpful response from Steady-Offload support, Ive got this working and here's how we did it.
On my theme I use custom fields, which seemed to cause a problem with Steady offload. To get around this we used a different method to 'offload images' that meant using the wp-offload plugin was NOT necessary and allowed the use of custom fields as well as ordinary image placements.
1- There is no need to install the plugin.
2- On your Steady offload account, go to control panel and then 'Integration'
3- You will see a one line java script with your unique key in it
4- Copy that line of java script and paste it into the header.php of your theme between the head tags.
5- Now do a search and replace of all your theme files and replace 'src 'with 'srcx'
6- This will now offload all your images to your 'Steady offload' account.
I'm still evaluating this system, but one thing is for sure, images DO play a large part in bandwidth, so this maybe a great concept. The downside is that image names are rewritten and will not be any good for SEO purposes
I'll post back here in time to make an evaluation of how well this improves my page loads, site efficiency and bandwidth.
Thanks to bl0wfish for all your help. This counts for a lot these days!