I had a baby in the summer too, it's difficult. I have a toddler too so there's a lot to juggle and my husband works a lot but he does try and help as much as he can. It's a lot though.
With my first I tried to do one activity a day and these were all out of the house. Now I've got two, my aim is get just one thing done, an activity or a chore. Basically anything in the hopes that it is achievable. I find it just helps to have a goal for the day otherwise all the days are just blurring together, especially during lockdown.
I would definitely try and meet up with friends for 1:1 walks.
Try Peanut and Mush to help meet local mums. Just remember there are A LOT of mums in the same situation, so everyone is extra friendly.
See if your Children Centres and NCT branch are running walks. These are group activities that are allowed, up to 15 can join.
Check Facebook for local groups. Children Centres, NCT branch group, local mums groups - my area has one specifically for lockdown babies too. There are also groups for your birth month (not local) which can be nice to join as everyone is at basically the same stage as you.
Some baby classes are running online, it might be worth signing up for one. Things like Baby Sensory, Kindermusik, Baby College, BusyLizzy to name a few. It's nice to have a bit more focused activities, the instructors are always lovely and they normally have a chat at the end with all the participants. I know one that does a specific newborn and chat session once a week too. As it's all online it opens up classes that you wouldn't necessarily be able to do if they were in person and online classes are fine for non mobile babies as it more like guided play.