So you're in an area with excellent public transport.
Why is it so hard to understand that this infrastructure just isn't there in the outer boroughs in greater London.
I've repeatedly used my own example. I have to have a blood test every 2 weeks at the moment at local blood test centre, and once a month at the hospital. My local blood test centre is 10 minute drive, but 3 buses and 45 minutes using public transport. At the moment, I can easily make up the 30 minutes it takes me at the end of my working day. But when it becomes around 2 hours, it's not doable. The hospital where I have the blood tests is 15 minutes by car, or 75 minutes or over by multiple buses (longer by tube). I would be expected to either make the time up, or take annual leave.
A friend posted on facebook - her elderly grandmother is receiving radiotherapy 3 times a week at a south London hospital just inside the zone. This means a payment of around £150 a month for her to receive this. In their early eighties, so changing the car isn't simple or affordable. It would be 90 minutes on public transport (into London on train, and then back out again to hospital, and then repeat for way home) for a sick, elderly woman.
An HCA at a hospital on London / Essex border. Works a shift that finishes at 11pm. She barely earns over minimum wage, and there is no public transport home for her at that time of night. So £12.50 each day, or £25 if she doesn't manage to leave till after midnight which isn't unusual.
Central London it's all very doable and easy. But before bringing it into greater London, the public transport needs sorting out.