You can now produce study packs using material already covered by the CLA licence without needing to seek additional permission.
Restrictions over the amount to be copied are as for Copying Books and Journals for Class Purposes. You can only charge production costs and not make a profit from the sale of the study packs.
The CLA has indicated that they would consider "compilations consisting of a series of chapters from ‘core’ student textbooks" to be in breach of the spirit of the licence. The CLA and Universities UK have produced joint guidance over what is considered to be a suitable course pack