Hi Pauline and Boo,
Thanks for your comments. My husband and I have discussed it and i know he is undecided also, like me he wonders how we will manage, i did have a chat with my doctor who is a mother and she said that she had to make a similar decision herself and like me her youngest at the time was five, in the end she decided to go for it and it has worked out very well for her. She said that her other two children have 'calmed down' since the baby arrived and are not fighting as much and she too is more relaxed about things.
I know it is different for everyone as all children are different, but it was encouraging.