We don't accept credit card payments.) Simply complete an application form and send it to us, with a cheque payable to NS&I. If you or a child you're buying for already have some Premium Bonds, you can buy via bank transfer (including standing order).
No - if you signed the bond it doesn't matter whether you have a job or not - or whether the bondsman asked you if you did. You are liable as surety on the bond - having a job or not has nothing to do with your liability. Sorry.
In reality, a bail bond won't affect your credit score in any way. However, bail bond companies may conduct a credit check before allowing you to get a bail bond to make sure that you're a reliable co-signer.