I'd just do a sleep suit. That's what I did with my daughter. Made getting her into the car seat easier I think.
I took my son home in pajamas and an adorable matching hat with teddy-bear ears. It also would have worked to just keep him in his swaddle and a long-sleeved tee, and then to unwrap the blanket once we got to the car when putting him in the seat enough to click the straps of the 5-point harness. The only thing to avoid is trying to get a kid clicked into a carseat with any kind of gown or sack on him that does not allow you to put the strap between his legs; then you have to un-click and undress and it is a nuisance.
I like to have the feet covered. Socks never stay on and it rains here in Oregon. I'd say pants or pajamas with feet. Easier to get into car seat the first time.
I'm taking my boy home in the cutest baby grow :) nice to find someone else from England where abouts are you Hun? Xx
I'm also from England :-) due Aug 1st! (however lots of signs already think it will be anyday now) with my first it was a pink babygrow set with knitted jacket. With this one will be a blue babygrow set with knitted jacket :-) easier and practical and they don't stay in babygrows for long - it's a forever memory. Good luck :-) xx
We are planning to just have our in a onesie.
I think it is more comfortable and there is plenty of time ahead to dress up :)