On Sat, 1 Feb 2014 04:09:55 -0800 (PST), puffernutter wrote:

Very simply, what do I HAVE to do to meet any building regulations, laws
etc.?

Look at the relevant building regs that are online in the "planning
portal"? Google will find 'em...

I don't think a liner is an absolute must but you'd have to be pretty
sure that the chimney is sound and stays that way. Woodburners flue
gases are also hotter and not diluted with air like those from an
open fire. There may be longer term problems due to tar condensation
in a relatively cold and high thermal mass chimney.

--
Cheers
Dave.