Steve Firth wrote:
I also make judicious use of a bending spring,
essential where you encounter joists in the wrong place. Sadly copper
tube is getting harder and thinner walled in most DIY sheds so bending
with a spring is getting more difficult. Not impossible, but difficult
and it takes a bit of practice.

Anneal the stuff as discussed here some time back. Heat the bit of
tube where you want to bend it, and a bit on each side, to redness,
then dunk it in cold water or play water on it to cool. It will
then be soft enough to bend easily.