Don't believe there were any planned DC-10 trips to Britain, not to say they would not do the odd substitute. They did do affinity-group charters to transatlantic points like Toronto (inevitably) or Chicago. Some summer seasons they leased in an extra aircraft from the likes of Sabena or Finnair. The DC-10s appeared fully based at Belgrade, unlike the 707s which got outstationed in the summer season to Dubrovnik, and were always standard first/economy configuration, whereas the older 707s were reseated to total charter arrangement.