Hi, we are 2 families travelling down south from the North West in August for a few days. We plan to spend our first day at Harry Potter tour in Watford as we are staying at the Watford North premier inn. We are travelling into London on the following 2 days and I note from the travel info that there will be engineering works on overhead train lines through August weekends. Can anyone advise us on the best way to travel into London? I have been trying to work out which tube stations etc but am starting to become "blinded by the science of it all" . I would appreciate your replies and advice on this matter.