Your options are kind of limited with a CD32.
the sx-1 and sx-32 will allow you to add a HDD and floppy drive, also some extra ram iirc.
The sx-32 pro has its own accelerator built in and also has the above.
These expansions are more expensive than a 1200 so it kind of defeats the purpose for your needs. Afaik you cannot use any other amigas accelerator in the cd32.
My advice is buy a 1200 mobo and expand on that and get the cd32 for doing what a cd32 does best. Sitting under the TV and playing games.