The court will take into account more than just the lack of the landlord's signature on an electronic document. They will look at the intention between you two,

The court will take into account more than just the lack of the landlord's signature on an electronic document. They will look at the intention between you two, as well as any correspondence between you and the landlord's agents. A contract does not have to be written to exist, although it certainly helps. An oral agreement that you'll continue in the lease and will treat the document as a formality would suffice. There will be evidence you will be able to adduce in your favour beyond this signature service. Furthermore, there are strict rules around eviction; the landlord can't immediately evict even when you're not on an AST.