Hi Dominique,
I’m not in Sevenoaks itself, I’m about 30 mins away, but know it very well (DH’s grandmother lives there, and he worked there for a couple of years) and I’ve been local to this area most of my life (moved back to be near parents when expecting DD).
Lots of things are not running at the moment, but normally there are lots of Sure Start centres with different activities on different days of the week, I’ve met some really lovely mums that way and have got to know them really well (although it does take a while, the first couple of times you go people don’t tend to say much as everyone is looking after their little ones). I’ve found that to be a far better source of mum friends than various activities to do with DD that cost money (Baby sensory, hartbeeps etc) - those ones tend to be very busy, so no time to chat, whereas the sure start activities are much more chilled and there’s more chatting time. If you have a car, you could go to a different stay and play every day! Lots of the local libraries have bounce and rhyme too, which if you have one in walking distance is really great as people tend to walk together and have a good natter.
Church groups are also a really great way to meet local mums if you’re comfortable with that - they tend to have designated cup of tea and chat times, so you really get to know people well and I’ve found mine to be really supportive. My DD has some wonderful friends from her group, and they are all really local so we could easily pop into each other’s houses for a cuppa when convenient (not at the moment obviously).
Basically, there’s a tonne of stuff laid on, and much of it is free (although there are paid activities as well if you fancy them, but might be better to hold off on those until DC is a bit bigger and nap/feeding times are a bit more predictable so you know what time of day is best for you). I wrote myself a lTitle timetable of what was on where each day. If DD was sleeping or I didn’t feel up to it, we didn’t go, but at least I knew there was something we COULD do each day. Now DD is 3, I have a tonne of local mum friends.
Don’t feel bad if it takes a little time to get a network. When your baby is tiny, they take a lot of you time and mental energy, and that will be true of the people you meet, so it can take a while to get friendships established.