Starting a new job how long after can I try for a baby ?

Typically companies want you to work for a year before taking maternity leave, so maybe give it a few months before you start trying.

Start it your body clock isn’t they for life but if they sack you they not worth it

If you’re referring to your entitlement to Statutory Maternity Pay. The law in England is work for an employer for a minimum amount of 26 weeks that entitles you to Statutory Maternity Pay ( see photo below)

https://www.gov.uk/maternity-pay-leave/

https://www.gov.uk/employee-rights-when-on-leave