How much can I copy from library materials (journals, books) I have access to?

Both printed materials and electronic resources provided by the library are normally protected by copyright. In practice this means that there are limits as to how much you can copy.

For non-commercial research and private study, you can download or copy under 'fair dealing' principles. Essentially this means that the amount you copy is justified by your purpose and is not likely to damage the market of the work. Copying a whole book is very unlikely to be 'fair'; copying one chapter may be easier to justify. A rule of thumb (not prescribed in the law) is one chapter from a book, an article from a journal issue or up to 10% of the work; however it depends on the context.
Copying from e-resources is subject to UCL's terms and conditions of use. In addition, you may come across restrictions when trying to download or print from an ebook. These limits may vary by publisher. See further guidance on using e-books.
If you want to make copies for students enrolled on a course you are teaching, this must be done under the terms of the Copyright Licensing Agency (CLA) licence. Setting up an online reading list for your course has several advantages, including staying compliant with copyright.