I got as far as the key bit and had to respond OP.
OK, as some have mentioned here, helpful people who pop round for 20 minutes or so 'arranged' and help in those early weeks are useful. If they do a bit of cleaning etc, drop round a meal or something, are supportive and most importantly sensitive....if they are just dropping in unannounced when you are recovering from having given birth then this could fast become a nuisance, already has....then thats just not on, things have to change...them letting themselves in to your home, errrr no, thats not really fair and would put me on edge quite frankly no matter how nice they are, you deserve some privacy and more than ever with a newborn you're getting to grips with. They sound like they are very friendly people and your DP is not wanting to rock the boat, he needs to realise that things do need to change, very few women out there would be comfortable with this arrangement. A quick call ahead to see if its alright to drop in, the occasional knock on the door fine but what you have at the moment goes way past that.
If you're planning on BF'ing you'll also want some space as it can be hard work getting started and the last thing you want is feeling uncomfortable doing that in your own home with an audience (I bf a 22 month old and was very shy and nervous around others doing it initially).
I talk from experience. My mother lived with us for 2.5 years which coincided with the birth of DS, in some respects it was good, in others, plenty of unsolicited advice, she hadn't BF any of us and had no idea that BF babies fed so much sometimes for an hour and then straight back on again and then the problems started. I was seen as being over protective simply wanting to keep the baby with me and not let her have him for hours on end. Anyway, my story differs a bit to yours but I do see your concerns and think you have every right to put your foot down.
Your DP and you should think about going to Antenatal classes, do a last minute one, honestly, they'll open his eyes on this and help him see your concerns I'm sure.
Maybe he should read this thread, your life and his is about to change massively, we all on here are out on the otherside and can tell you that for a fact, perhaps he should read some of the advice and see that you are not being unreasonable and its time he made some rules for his new 'family'. Doesn't mean distancing himself from his own family, they just need to be a bit more tactful and give you some space, it seems suffocating and possibly the ultimate ruin of your relationship.