Le site ukdeedpolloffice.org est-il sûr ?

This website belongs to a private company which, in return for a fee of £14 (at the time of writing), will "draw up" (i.e. write out, or type and print) a deed poll. Drawing up a deed poll is a common law process - it's free, and you can do it yourself. You do not have to use a company or law firm in order to change your name. All this company seems to do is type and send you the document: you can find several websites which will help you do this for free. Even if you use this company's services, you will still need to get the document signed (by you) and witnessed (by two others), so don't think they'll do everything for you.