Where do I paste the first code? The revision I've got already has the new sheet with getccprices code. Thanks @LukeStokes.
Poking around more I assume it is Tools > Script Editor
And I imagine it is expected that you must grant authorization for the script to access your Google account? Which it makes sound very imposing.
Yes, the script editor. The version I'm using personally does have script access, I think, which is partly why I haven't bothered to update the publicly shared one since many may not be comfortable doing that. The main benefit, I think, is having a button I can press to refresh the rates.