Physically, I had 2 C-sections, both time I was out for short distances (e.g. the pub) by the end of the week, and normal distances around day 10. Hiking with baby in the sling by week 6.
Then the hardest and most unpredictable part is the baby itself... With baby 1 I found it really hard, not that much the first 6 weeks but after that. Most babies sleep a lot the first couple of months, then they start to wake up and cry a lot more! It felt like hours and hours trying to put baby to sleep, and I was very lonely. The best part was lunches etc with my NCT friends.
With baby 2 it's much easier: she sleeps better, breastfeed better, is much calmer.... I feel a lot more relaxed because of that and enjoy my mat' leave a lot more too.
You can't really tell what your baby is going to be like, it can be really hard if they cry a lot/don't feed well/have any other health issue, or really easy. But the hardest part in my experience is not the first 6 weeks, apart from the feeding which can be a bit tough at the start if you breastfeed.
My advice is to try and meet other pregnant women around you now (with NCT, pregnancy yoga etc), and get some WhatsApp group(s) going. Even if you don't meet up much socially now, you will once the babies are there. It's really comforting to share your struggles with others in the same boat, and mat' leave means lunches and brunches out on weekdays when people are at work - I love it!