Congrats on your LO!
I'm a rubbish saver at the best of times, but I'm in the same boat as you...... we'll be saving whilst I'm on mat pay, so not really the ideal saving scenario!
The piggy bank idea is a good one - we've done this and it really does add up! I don't know who you bank with either, but I bank with Lloyds TSB and they do this thing called 'Save the change' so that if you use tyour debit card somewhere, they round up the transaction to the nearest £ and put the change in your savings account... i.e. if you spend say £9.99 somewhere, they transfer 1p into your savings or if you spend £5.67, they'd transfer 33p etc.... I think that's quite good!
Also as I'll be on mat leave, I'm planning on doing a few more bits and pieces myself to cut down costs e.g. our wedding favours.... I'm going to pick up the bits and put them together myself.
The other thing I've started doing, is doing my 'big shop'online. That way I tend to buy much less crap than i would be inclined to do when walking around the supermarket, good too for all the heavy stuff and baby stuff and I imagine much easier than shopping with a newborn!
Best of luck! When's your big day?