I just decided I ought to use https for accessing my Owncloud calendar and contacts so needed to configure a certificate for my isbd.uk host (it's a Gandi virtual server).
My Google search for Ubuntu https showed LetsEncrypt as the second hit so I took a look, seemed sensible so I followed the instructions at:-
https://www.digitalocean.com/community/tutorials/how-to-secure-apache-with-l...
Absolutely brilliant, not only did it generate a certificate for me, it did all the Apache configuration too so https://isbd.uk worked after I'd run the commands given on the above web page.