You may well have to remove the cams to get the heads off mate. it depends if you can unbolt the head studs with the cams in place.
I know with ARP studs it is possible to do it but not tried it as a whole TBO
They can be removed without the special tool but the cam caps MUST be kept meticulously in order (numbered or whatever) with their own cam journal.
I cant remember if the journals are numbered but if not number as you remove .
On a 325i I had to drop down the oil pan, rand remove the vanos unit and timing chain to help a friend do his head gasket. But we had the Cam removal and alignment tools and he installed Schrick cams at the same time.
Does anyone know a BMW special tool hire source in the yUK?
its a major PITA not being able to get some of the tools as they are so expensive for single use jobs
This is a very good article on removing them even tho its the US engine
Cam removal