The SE is vv crowded & expensive. dh says he'll never live there - in fact, he doesn't ever want to return to the UK.
however, i grew up in s.borough & my parents are still in the house they moved to when i was 2, so it is very much 'home' for me.
there are advantages - easy to get to france, day trips to london (btw, my mum always took us to cultural things as kids. not appreciated at the time, but now i realise how grest it was to see changing of the guard, museums, art etc). whenever i'm back in the uk i give myself a day & eve in london cos even though i never lived there. i still miss it.
if you think about villages outside tw, look at the cost & convenience of parking - it will add to the cost of commute.
when talking to estate agents, be VERY firm about school catchment areas - the areas for 'good' schools can be pretty tiny - estate agents will happily tell you 'it's in the st johns area' but it could be in a different school district. if in doubt, phone a head teacher to ask if they'd consider taking your son.
i was house hunting in tonbridge last summer, so know, almost street by street, what they are like - feel free to keep asking. i also have a friend who has done supply teaching all round tw & tonbridge, so can get you the 'insider' opinion of a school. some places can have a good/bad reputation, but be completely the opposite because of the staff.
based on my friend, i would say avoid high brooms & sherwood completely - both school & housing wise.