At last the Land Registry has moved into the modern age and recognised electronic signatures. They are now accepting dispositionary deeds (such as transferring , creating leases and securing mortgages) that have been signed with a witnessed electronic signature.
Here is a link to the updated Practice Direction: https://www.gov.uk/government/publications/execution-of-deeds/practice-guide-8-execution-of-deeds
Here is a link to the article on the Land Registry website: https://hmlandregistry.blog.gov.uk/2020/07/27/electronic-signatures-in-practice/
If you're looking for a reliable method to do this we can recommend some software that we sue for electronic signatures.