Adults take nectar from a range of flowers including:
In the autumn, caterpillars seek out a suitable pupation site, usually a hard surface such as a wall, tree trunk or fence. Once a spot has been chosen, they carefully attach themselves to it with silk, before turning into chrysalises. They’ll spend the winter in this form. then emerge as adults the following spring. Occasionally they choose a warmer location, such as a conservatory or greenhouse, and will develop faster and emerge earlier.
There is even more about this species on the main Butterfly Conservation website
Whilst resting, this butterfly will sometimes disguise itself amongst white flowers or against white-patterned (variegated) leaves.