You'll need to buy a maxi rider car seat for N, because with the new law changes he wont be able to legally be in an ordinary booster. The new bub will only be in a capsule for a little while and then bubs will need the car seat N is in now, and he'll need the maxi rider (or other 5 point harnessed seat). When our second came along, we kept L in the cot till E was big enough to go into it and then we put L in a single bed, so that's something you may need too - I really can't see the point in getting a second cot when he could be 2 or older when this bub is born and will be ready for a big bed anyway. You'll need a second lot of bedroom furniture - drawers, wardrobe etc. Plus if you wanted to do a new room for N and keep his room as the nursery etc. But that's stuff that can be done later anyway, so you don't need to do it all at once. Then if they are different seasons, then there will be clothes you'll need etc. I know you do a bit of walking, so getting a toddler seat on your pram might be the way to go - not sure if the buggaboo has that attachment (they have every other bell and whistle, so I imagine they would LMAO)