The LawBod uses Library of Congress subject headings, sometimes you have to use US spelling or terminology eg to find general works on English employment law you have to use Labor laws and legislation -- + jurisdiction (Great Britain or England) to find works on Trade Unions use Labor Unions - law and legislation.
The principal shelfmarks in the English labour law collection are:
|KN190||Industrial law and relations|
|KN191||Right to work|
|KN192.1||Contracts of employment|
|KN193||Conditions of employment|
|KN195||Trade unions, associations etc|
|KN196||Trade negotiations & disputes|
|KN198||Health & Safety at work|
Works on labour law for other jurisdictions will be shelved among the general textbooks (with 510 in the shelf mark) for that jurisdiction.
The first two are in the Law Reserve Collection as are on Reading Lists. The rest are on open shelf in various areas of Floor 2 - but holders of an Oxford SSO could also read a couple online via the title link
Books with a shelf mark beginning Jurisp can be found on Level 2, the entrance level.