Over 14,000 UK Treaties, both bilateral and multilateral, are available on the UK Treaties Online website. A Treaty Search page allows you to search by type of treaty, entry into force date, place of signature, and/or signature date.
Treaties and other international agreements to which England is a party are published as Command Papers. Command Papers include both ratified and unratified treaties and other international agreements. Command Papers are published in a numbered series and include a prefix to identify "command" as follows:
Command Papers from 1996 - current are available online from the UK Treaties Online (UKTO) website. Command Papers are organized by date and by subject matter. Command Papers prior to 1996 must be accessed in print. Use Worldcat to find a library and then request via interlibrary loan.