I'm in inner city Leeds, Yorkshire so there's no point in southerners
bothering to reply - conditions are very different :-)

I want to get an apricot tree, I'm assured that they will produce fruit here
if grown in a protected, sunny site.

I can do that but not with a wall behind it, which is recommended, unless we
build one which would have to be done from the friendly neighbour's garden.
He's co-operative and wants to build a garage in that spot anyway -
eventually.

The site is reasonably sheltered and gets full sun (when it's out!). The
local temperature is higher than in less built-up regions.

Would it help to put a temporary panel of a less heat retentive material -
wood, plastic, glass - until a wall can be built?

Would the panel (hem!) advise training the apricot as a fan or other shape
or having it as a small tree? I'd prefer it to be flat against the
fence/wall.

Do I need to know anything else?

Mary