Wanted: Aerial for '89 VW Golf CL

Hi,

First off I know little about cars, and only a little more about
radios.

My friend has a 1989 VW Golf CL and has had the aerial bent off. I
called a VW dealer who said the replacement part was discontinued. It
is the wing fitting type and is manual, not automatic/electric.

I know Halfords makes 'universal' aerials - should I buy one of these
(if so which one?) or is there a replacement pattern part which is
better?

Also, is there anything I should know about fitting it?

Thanks in advance and there's a bar of chocolate in the post to whoever
gives me the help I need first!! (seriously!)