Ubuntu 18.04 is available for OpenVZ 7. We are in the process of migrating all OpenVZ 6 servers to OpenVZ 7. If your VPS has already been migrated, you can request access to the Ubuntu 18.04 template. It will be generally available once all OpenVZ 6 hosts have been migrated.
We offer Ubuntu 18.04 on KVM (cloud) if you need it immediately and have not been migrated yet.
Updated: Nov. 1, 2019