Personally I would go as big as I can now that you have the opportunity to do it. I had a 4.5kg simpson for years - I brought it when I was 19 and only just replaced it late last year with a 9kg simpson and that was after doing the washing for 6 people for a year in it. Anyhoo, I think that's what the baby bonus should be used for - you're going to wash the baby's clothes in it, you are going to have extra washing created by having an extra person in the house. And back when my 3rd was born and the baby bonus was being introduced in 3 days time, the midwife and I were talking about it and she said even buying new tyres for your car is something worth while to spend it on because you are making sure you have a safe car to get you around in kwim?