I used to walk to the station every morning. There is a hill path up and down, as long as you are fairly fit you can do it in 15 mins.
It's about a 15 min walk to Sydenham station too.
The number 3 bus used to stop outside. If you have a car there are garages for hire behind the properties.
Lammas Green is a proper community. I felt very safe there. No cars allowed inside the green for extended periods meant the kids could play safely.
They have a little community hall between the houses and flats - you can hire for parties etc, and they run a crèche and fitness classes there.
It's leasehold, and they have a strong committee running and challenging the annual fees and bills. It's grade 2 listed, but that just means the outside of the property has to be maintained in keeping with the style of the green. The Lord Mayor of the City of London is your landlord, there is minimal ground rent and he comes to tea with the residents every year. 
You can be involved as much or as little as you like tbh. I worked long hours and was a single woman so it was nice to know that the grounds were being maintained, place was patrolled, it was safe, clean and cared for.
I've been to a few of the houses for a BBQ, party. They are pretty spacious, traditionally laid out houses.