change of signature

[Pimpernel]

Hello,

I am thinking of changing my signature as the one I've been using for above 20 years is fairly easy to forge.

Where do I get the new signature recorded 'officially' for ID, NINO, Inland Revenue etc.? I think banks have 'Change of signature' forms where you can submit both your old and your new signature, but I'm worried about failing to notify another important third party.
Is there a fee (besides the one for getting a new passport)?

Thanks very much in advance.