Capital Gains on Crypto

Can I ask, if you have made no gains of losses on digital assets in that year, do you still need to declare anything and if so, when is this required to do so?

Hi,
You are only required to declare gains to HMRC.  
If you make a loss, then there is no requirement to declare it. If you want to carry the losses forward to set against a future gain, then you need to declare the loss either in writing or in a Self Assessment tax return. In either case, supporting evidence is required.
Thank you.