That is more or less what I did. I went down to a plumbing supplies place and explained to the nice man behind the counter what I was trying to make.
I ended up with some soft copper pipe, 10mm I think, some thick, clear plastic hose and one of those fittings for attaching your garden hose to the tap.
I wound the pipe around a large pot, just like you are proposing doing with a cornie and attached the plastic pipe with plumbing tape, gaffa tape and colourful language. It took me several tries to get it to stop leaking, but I got it in the end.
Mash tonight, boil tomorrow?