A Peugeot Partner is a commercial vehicle. Although diesels have to comply to EOBD from 1st jan. 2004, the commercial vehicles do not yet. They have to comply depending on weight in 2006 or 2007. Checked this recently on a 2004 Partner, it was NOT compliant.
If it's not compliant there's not much use for an Elm-interface.
Find someone with a generic EOBD/OBD2 reader and find out if the vehicle communicates first, before spending money.
N.B.: OBDII is only used in the USA, not in Europe.