Don;t bust a gut over it, as long as the frost stays off in winter, and you open vents in the summer it should be fine.
Folly save your £££ None at this time of year , close the window at night if you think a frost is on its way Spruce
That's the theoretical temp for cucs Freddy. Toms can stand it quite a bit lower but though low temps won't kill them they can set them back.
