Raising any child, even with help, is difficult.
Raising a child with no help at all is obviously even more difficult - but lots of us do it!
The first few months will be very tricky, until you get into a routine. After that, I recommend you get out to as many mother & baby groups as you can, to build up your circle of friends. It's very easy to make friends if you have a child, as long as you put the effort in & invite them back to your place for a cup of tea etc.
The worst thing is when they or you are ill, as you just have to hunker down at home and cope with it yourself. At least these days you can get online supermarket deliveries, so you won't starve. For very serious illnesses requiring hospital stays, I have found that most hospitals let single parents (& small sibilings) stay overnight. I've been in situations where I've needed to take one child to A&E in the middle of the night, with no-one to take the other DCs, so have had to wake them up and take them too. It's not ideal, but you do what you have to do.
Juggling work and children on your own can be very difficult. You may find you end up changing careers, or only working PT. You may well get child tax credit and working tax credit though, to help fill the gap.
The main thing is - do you want the baby? If you do, you'll find a way to make it work.