Just to clarify the first letter is defiantly "P" and not a "F".
P codes are for program setting\calibration, and generally is used when commissioning the boiler to make sure all the components are working, F codes are fault codes and indicate there a hardware failure of some sort.
I can certainly help talk you through some troubleshooting steps in either case, but want to make sure im not going off in the wrong direction.
Right F61 is a hardware fault to do with the gas valve.
This may be a lose wire, or a defective valve \ actuator, at a guess you have the unit heating a hot water cylinder so its activating at night to heat your hot water and then generating the fault for you to see in the morning.
Either way this will need a gas safe engineer to attend, and check the cables are correctly connected, and potentially replace the valve\actuator, this is a rather simple task as you dont need to strip the unit down to get to the valve.
If you would like me to recommend an engineer, please provide your postcode.
Please let me know if you have any follow up questions or need something clarified.
I havent heard from you in a few days, and I just wanted to follow up and check if you required any further assistance, if you question has now been answered I would appreicate if you can rate the service received.