Hi @Harry_Rowlands , welcome to the forum 
I totally feel your pain! Support for dashboards in project templates is desperately needed!
You can vote for that here:
and use this workaround if you can afford to loose out on the project template features such as dynamic dates and dynamic roles. So, currently, it’s a bit of finding the right balance and what works best for each use case; i.e. using project templates or simply duplicating a project called ‘template’ .