How do I travel between Croydon and Swiss Cottage while avoiding Zone 1 trains?

Catch a Southern train from East Croydon to Change at Clapham Junction on to a London Overground train to Willesden Junction where you change on to another London Overground train to alight at Finchley Road and Frognal Station, which is a 7 minute walk from Swiss Cottage. Despite the 2 changes this is quite a fast and speedy route

www.nationalrail.co.uk

https://tfl.gov.uk/fares-and-payments/fares/single...

Avoiding Zone 1 via Clapham Junction, Willesden Junction and West Hampstead

saves £1.20 peak, 60p off peak

certain alternative routes involving changing between National Rail and London Underground at:

London Bridge

Victoria

Blackfriars

Cannon Street

Charing Cross

Elephant & Castle

Balham

Waterloo East

are more expensive