We are arriving in London and staying at the Hotel comfort Inn out near Heathrow. We wish to go to Potters Bar from Heathrow to Potters Bar and believe thatw e take the train into Paddington and then catch a train out to Potters Bar. Is this correct and also when we change trains at Paddington if this is the correct departure point which platform should be go to for the train to Potters Bar. Your assistance would be appreciated.