Hi @andypearson,
Welcome to the 
community support forums !!
You can upgrade to any newer version of Grafana as there is no special roadmap. What is important to know is that before doing the upgrade, make a backup of your database as described in this documentation.
Also, there might be some graphs/visualisations which might not look the same as in ver 8.x as those changes are described in the release notes.
Lastly, you can follow this active post where many users posted some very valuable information when they had performed the upgrade.
I hope this helps.