On Sep 25, 8:33 pm, Andy Dingley wrote:

Douglas Fir might be your best all-round choice. Good structurally,
light & strong, pretty good rot resistance. Easier to buy from non-
specialist yards too.

Can't you get timber in the UK that is treated against rot?
In NZ we would use H3 treated pinus radiata, as Douglas Fir won't
absorb
the treatment well, and only lasts a few years outdoor if untreated.