Pickle - don't panic. You will be eligible for some help if your income is low. I found using the calculators almost impossible because they ask you what you earned in the previous tax year, which for all of us (or those of us whose careers I have some inkling of) will take us way over the threshold for receiving any help.
Disclaimer: none of the info below is definite; I'm doing this off the top of my head...
SMP (maternity pay) is £140pw, but most of you might be able to get better maternity pay than that from your employers.
Child benefit is something like £20pw
I think that while we're on maternity leave if you're only on SMP we are eligible for some child tax credits (I worked it out to be around £240pcm)
Once you are working again, 16 hours per week, working tax credits kick in and actually I think its a decent amount (can't remember how much but several hundred per month).
If you're 'low income' which obviously I'm not now, but most likely will be once I start working again in January, then when your child turns 2 you will be eligible for 15 hours a week free childcare, then 30 hours a week once the child is 3.
Obviously its going to be a huge drop in income for most of us, but I think for the short timescales involved until free childcare starts to kick in its probably possible to muddle through.
I have been reducing my direct debits by switching to a £10pcm mobile contract (still has plenty of data for satnav, emails etc.), moving broadband suppliers etc. I've got to the point where my bills (mortgage, utilities, council tax, phone etc.) will definitely be covered by the SMP and child tax credits.
I think as long as we meet the 'low income' criteria we are eligible for a reduction in our council tax bill and my utilities company offer £160 off per year if you're on a low income. I'm just not 100% sure yet as to how the fact I will have earned well in the tax year 16–17 will affect that.
In all honesty, for me, any social life (going for coffee with other mums for example) and purchases are likely to be going on a 0% credit card until I start earning again (phased return to my freelance work from September but only four hours per week to start off with).
I have been stocking up on non-perishables (tins, pasta, cereal) and have a year's supply of washing powder, shampoo, toothpaste etc.
I think my parents are planning on being generous with things for their grandchild while my money is tight so that will obviously help too.
If I haven't starved to death by Christmas
, I'll come back and report on any financial help I have found/received.