Lord and Prof titles
Looking at this link, Professions, as provided by erstwhile editor in the comments to your question, the answer would be Professor Lord [Such-and-such]:


  If a professor is also a member of the peerage, or a knight or dame, the academic style and title may be combined as ‘Professor Lord Ryder’ or ‘Professor Dame Elizabeth Pulteney’. He/she may prefer to be known by title alone.