However, as I went for bigger modules, anything that had dependences were then failing as the dependencie were installed OK but then did not appear to be available.
CPAN on CentOS 7 doesn't install things in the system locations by default (and by design). This is to stop CPAN from over-writing files that actually belong to rpm packages.
A number of things you can do. The sort of recommended way is to package the perl modules into an RPM and install them that way (so that the package managers know about them and can resolve conflicts). There are progs to do it for - look for cpanspec.
CPAN will install the modules in ~/perl5/... by default - the "real" way of doing things is to @INC that location at the top of the perl script or set environment variables appropriately.
Finally, if you must, fiddle with the CPAN configuration to install them in a system location. But be aware that things might get confused or break.
P.