Tomorrow, I’m going from Huntingdon to Farringdon for work. Then later, I’ll go to Watford Junction for a nearby interview and then come back to Farringdon for the rest of the work day. After about 6pm, I’ll go to Bank to have dinner with a friend and then come back to Huntingdon through King’s Cross. What’s the best value ticket for this day? Can I just buy Huntingdon to Farringdon, then use PAYG Oyster or would it be too expensive?