If you are working in the Law Library then you can use a copy of Raistrick's Citator.
These are available throughout the Law Library (plastic holders located at the end of the shelves).
Donald Raistrick, Index to Legal Citations and Abbreviations (4th edn, Sweet & Maxwell 2013)
[Image courtesy of Sweet & Maxwell]
If you are working from home then we recommend you use the Cardiff Index to Legal Abbreviations which is available online: www.legalabbrevs.cardiff.ac.uk/