Hi Lars,
The Minor Planet Center will be able to provide an Ephemeris via web page https://minorplanetcenter.net/iau/MPEph/MPEph.html. You will need to use C/1980 Y2 for the comet name and then add the date you want such as the discovery date of 19801225 and then an ephemeris will be created such as that below for a geocentric observer. You can change the observer location by adding an Observatory Code (e.g. 000 for Greenwich which will be sufficient for the UK).
