Just a quick Thanks for all the advice, I plucked up the courage and put my hands into the bag today (with marigolds on!) pulled out the skin which looks like its the rump as there was still the tail tube attatched.
I washed it then scraped off any remaining fat or meat i could get at and stretched it out on a board and laid it slightly at an angle to drain off, then covered the whole skin with a generous layer of salt, i'm going to get some borax for next week when i'll scrape that first layer off and recover.
Don't think it will dry for a good while in my damp shed though.
I'm now in need of a good bath and can I say i foiund the whole process totally un-enjoyable

that was probably without doubt the most disgusting thing i've ever made myself do! and i cannot get the smell out of my nostrils!
In future i'll stick to buying small patches i think