There’s no need for a seal on a deed. And generally, there’d be no value in forging a deed of name change, because it’s (basically) useless to anybody but you: all it is is a personal declaration that you’ll be using your new name (and expecting others to do the same) from now on – it’s only of any use to an identity thief who’s already capable of impersonating you perfectly (and for some reason wants to do so under a different name!).
A deed poll is the simplest and best way for you to change your name to your maiden name or to any other name you want. Give freedeedpoll.org.uk a go, and let me know how you get on! Good luck!