Thanks everyone 
Things are looking a bit more optimistic now. I looked at our spending in more detail with the Moneysavingexpert spreadsheet and it turns out we just need to cut £400 rather than £1000 in order to 'break even' each month.
Of course, it would be better if we managed to cut spending back more than that as that way we'd actually have more of a buffer and perhaps even be able to put a little bit in savings. We will still be £1000 worse off a month thanks to my redundancy but oh well - I suppose it's only a case of tightening the purse strings for a year or two while I'm settling down with the second baby and seeing my first off to school.
I appreciate all the advice about using cash and I do think this is a really good way of restricting spending, however there is simply no way I will be able to convince DH that we should stop using our card.
He actually works for a credit card company so he is really familiar with all the legal ins-and-out, he likes having the purchase protection, accumulating points/airmiles, and being able to see nearly all purchases going through one account...
However to make myself more aware of my own spending I am going to start writing down all purchases that are not part of the weekly grocery shop. So far this month the only purchase was a yearly pass for a local kids attraction which was only £13 - works out really cheap for toddler days out!
I am quite pleased with myself as I managed to almost HALF my phone bill from £23 to £11 a month! And then, because DH is with the same company, I negotiated the same deal for him too, despite them making a fuss about it at first, they caved in and put him on the cheap deal too! So that was an easy £20 a month saving in total 
I've also worked out if we just allow ourselves one bottle of wine per week that should save quite a lot of money. And I think I've managed to (in theory at least) knock over £100 off our food shopping budget by limiting ourselves to 1 bottle of wine per week, taking packed lunches instead of eating in the work canteen, limiting 'expensive' meals like steak, and trying to incorporate at least one or two budget meals into the meal planner. Obviously it's only the beginning of the month so it'll be interesting to see how much we save in reality. Food this week is costing about £100 in total... I didn't have to stock up on any cheese, loo roll, nappies etc though this week so I can see it being a bit more than £100 some weeks.
The money doesn't dry up for another 9 months or so as I'll still get maternity pay and a redundancy package but I thought it would be good to start being frugal NOW rather than panic when the money dries up!
Just trying to find a good buggy on a budget now - the only thing we really need to buy for our second baby as we kept everything else from the first baby.