Sorry Noniks, this may be the most unhelpful post ever, but the fact is you're unlikely to know what to do until you've already done it. Because no-one's experience of having children is the same, and no-one knows how they're going to feel about being a mother until they become one.
When I decided to have DS (aged 31), I had a pretty high-flying career and a great lifestyle (lovely DH, great holidays, lots of material indulgences). I had never wanted kids, and neither had DH. But it suddenly struck me that nothing in my life (apart from DH) really satisfied me in a deep-down way. I would sit there on a Sunday night and think to myself 'but what does it all mean', and I suddenly realised that only moments that brought me the kind of real satisfaction I was looking for were incredibly few and far between. And I got a bee in my bonnet that the answer must be having a baby. DH was pretty unimpressed - he still didn't want kids - but in the end he decided that my (sudden) desire to have children was greater than his desire not to.
So, we took a massive gamble and went ahead. And in our case, it massively paid off. I have a wonderful DS of 3 and a newborn baby of 6 weeks. I gave up the high-flying career to be a SAHM and I absolutely love it. I no longer ever have those Sunday night 'what does it all mean' thoughts, because my children provide all the answers I need. Everyone I know was stunned when I 'gave it all up' to be a mum, but I've never looked back. BUT I'm very aware that it could have gone very differently. I might have hated being a mum, and in lots of ways my decision was a very selfish one, because it could have been dreadful for my child(ren) if that had happened. (Incidentally, my DH adores our children as well. I think he misses our old life more than I do, but he still wouldn't go back.)
So, in the end I think it's almost impossible to make an 'informed' decision. Even on a practical level, because everyone is different. In some people's eyes I 'sacrificed' loads of things to become a SAHM: we have no disposable income so we never really go out and we can't afford indulgences; we haven't had a family holiday since DS was born; I get almost no time to myself whatsoever because I'm a full time mum (the odd morning off here and there before DS2 was born, but unlikely to happen again for several months now). But I don't really give a monkeys about any of that, because I've discovered that I love being at home with my children most of the time, and I'm actually reasonably domestic. (Obviously I do miss some things - main ones are probably holidays and days out with DH, pottering around an art gallery or something; though we have managed a couple of weekend city breaks on our own since DS1 was born, which have kept me sane.) But other mums I know choose to have totally different lifestyles: they work full time so have lots of time to themselves (or at least lots of 'adult' time); they maintain their disposable income so they can afford holidays abroad and nannies or babysitters. They couldn't bear my lifestyle and I couldn't bear theirs - but the point is, you do get to choose how you want to manage your life, to some extent.
As I said, not terribly helpful, because however much you try to imagine what life will be like and how you'll feel, it's almost impossible. Though the one thing that is true for every parent is that it is a completely full time responsibility. Even if you work out of home full time, you NEVER switch off from being a parent, not for a single waking second, probably for the rest of your life.