Which certificate do I need after changing the fuseboard and meter at home?

The legal way forward for you now is to contact your local authority Building Control Department and inform them that you have already carried out Part P notifiable electrical works, but would like to notify it. If they decvide not to prosecute you for breaking the law (Potentially a £5000 fine), you will be asked to pay their Part P fee, (normally about £200 - £300). Their inspector will arrange to come and look at the fusebox and carry out the testing. Providing the work is all fully compliant with BS7671:2008 they will then issue you with and certificate that you can fax to your electricity supplier.

I cant quite believe what im reading.If you actually carried this out yourself,you are lucky to be alive:) Oh,and its illegal.

You required Electrical Installations Certificate. But you had to notify Building control before you start that kind of job( if you have enough knowledge and experience, I not believe you have). This is job for professionals only, must be done all necessary testing and you must have test tools and calibrated torque screwdrivers as well.What you did could bring your house in dangerous.

I hope you revised the 17th edition first. You cannot get anyone to certify your work under their name.