I wasn't sure I'd ever have children. I had no maternal feelings, no broodiness to speak of. I got to 35 and thought well if I am going to have children I ought to have them now.
I have two DC- I enjoyed both my births ( not everyone has a horror story) and I loved the baby stage (most people don't) but I do find parenting all consuming and very hard at times.
You can ,however, make it easier or harder for yourself as besides temperement (which you can do nothing about) parenting style does count for a lot.
So whilst I have been having disturbed nights and children in my bed for 5 years, there's no guarantee you would as you might decide to put your baby in their own room, get them into a routine early on. You might decide to formula feed or express milk not insist on breastfeeding them until they are toddlers. You might practise benign neglect not helicopter parenting.
As for lie-ins it depends entirely on your relationship. If your Dp does his share of parenting you will find it easier than those whose partners don't pull their weight.
I don't lie-in because I've lost the ability to do so. I can't switch off whilst the children are in the house.
As for the things you can't do, you may find that the tiniest things give you so much pleasure when you are a parent- a cup of tea in peace at the end of the day is my idea of heaven. I no longer want to go out socially. I don't miss drinking. If you do you just have to find ways round it, socialise/entertain at home, go out seperately or book a baby sitter.
It was only when I became a parent that I really knew what I wanted to do and realised just how much I had wasted my childfree years. I am now working towards realising these ambitions despite having children.
You never know how it will change you but it will change you for better or worse.
Do not go into it lightly though. I am glad I have my children (even though on bad days you are on your knees) but I do think I could have lived happily without them too.