My partner is away and has been for about half of our 3 1/2 month old daughters life, so I have an idea of what its like to care for a baby without assistance. Of course, I'm living with my parents for the moment so I have their help, by the sounds of it, you won't be so your situation would be different.

Having a baby can be sooooo stressful and difficult if you're doing it by yourself. It can be anyway, but having no partner (or just a very uninvolved one) can take you to breaking point. Like if baby has a cold - she won't eat because she can't breathe, but she's hungry, so she just cries and cries and cries. Not to mention, she's feeling sick, and that babies really don't like mouth-breathing. That interferes with baby's sleep, and yours, and you end up stressed to hilt and sleep deprived and feeling terrible that baby is so upset and you can't help! It's hard, hard work. I don't think I'd ever be able to do it alone. Even on a day-to-day basis, when you're alone, you can't do ANYTHING for the first few months. As soon as you put a pot of pasta on, baby wakes. As soon as you hop into the shower, baby wakes. As soon as you walk out the door to hang up the washing, the baby wakes. It's so hard without an extra pair of hands just to hold them for a minute so you can bathe and eat! Though this does get better, its like this in the first few weeks/months.
But
I think having children is the same thing as being in labour (sometimes) - its impossible, but you get through it somehow, because you have to.

It must be horrible to be in your position. Having a baby is SUCH a huge decision, and doing it because you don't think you'll have another chance may not, in my opinion, be a good reason. Then again, my baby was a surprise baby (that is, an accidental pregnancy) and I am absolutely wrapped to have her.

If your partner doesn't want a baby though, then I don't think he's a good choice. A pregnancy that one partner doesn't want creates a whole universe of trouble, believe me! And if you really want to have a baby and this is your only chance, you may regret it if you stay to him, particularly if the relationship ends for whatever reason and the opportunity for motherhood is over for you.

I really don't envy your position, but I'm sure you'll make the right decision for you.
Good luck.