I understand that the 60+ London Oyster Photocard is valid in London Zones 1-6 after 9:30 am.

Epsom Downs Station is in Zone 6 but if I prefer to travel to Epsom,
Epsom Station is in London Zone 9 (60+ London Oyster Photocard is only valid as far as Ewell East Rail Station).

I would usually prefer to catch connecting trains from London Bridge.
Southern to Epsom.
or Southern to West Croydon and Southern to Epsom Downs.

However, I am unsure whether my 60+ London Oyster Photocard would be valid on buses from Ewell East to Epsom.
There are two connecting buses from Ewell East which should take me to Epsom.
S2 bus to Hessle Grove then wait for the E16 bus to Epsom Clock Tower.

I understand that it is possible to purchase an extension ticket for the 60+ London Oyster Photocard.
Please advise me of the most straightforward method of purchasing extension tickets for the return journey on the day of travel.

I would also need to establish the procedure which should be used to purchase extension tickets for travelling companions with Freedom Passes.