xubuntu 17.04 cant be updated to xubuntu 17.10

xubuntu 17.04 cant be updated to xubuntu 17.10 presumably because canonical have deleted the release files so never use a non-LTS version in the future

The repository 'http://gb.archive.ubuntu.com/ubuntu zesty Release' 
does no longer have a Release file.
Updating from such a repository can't be done securely, and is therefore disabled by default.
See apt-secure(8) manpage for repository creation and user configuration details.

The repository 'http://gb.archive.ubuntu.com/ubuntu zesty-updates Release' 
does no longer have a Release file.
Updating from such a repository can't be done securely, and is therefore disabled by default.
See apt-secure(8) manpage for repository creation and user configuration details.

The repository 'http://security.ubuntu.com/ubuntu zesty-security Release' 
does no longer have a Release file.