What car to buy?

Hi everyone. The names Mikey and I'm new to the site. I was hoping some of you may be able to help. I have my driving test on Monday morning and if all goes well I'll need a new car. I currently have a mkiv 1.4 golf but this is no good for me as it has a lap belt in the back. I have 3 children so I need 3x3 point rear belts. This is where it gets hard for me. I am 22 years old and unemployed due to looking after my kids as there motheris suffering from P.T.S.D. This makes it hard to get insurance.

So long story short I need a fairly big car for under £1000 that isn't going to kill me on insurance. Any ideas?

Thank you.