Blaupunkt do an in-dash CD changer unit and i was considering getting
one to fit along with a standard Blaupunkt headunit in my Corsa C, but
the 'double DIN' space left by the factory fit stereo isn't quite big
enough for two single DIN units. Such an arrangement would be better in
an Astra G which does have two seperate DIN sized spaces.
Have you considered the Vauxhall CD changer & tape player unit? I think
it's CCR2006 and comes as an option on the Corsa (and standard on
some/all SRi spec). They occasionally appear on eBay (or you could get
a new one from Vauxhall but they'd be quite pricey I imagine).
Should just slot into the space vacated by your current stereo and you
get a tuner, CD changer and cassette player all in one unit in your
dash.
Tariq