Hi Kate,
Hedges have to be managed at some point, otherwise they turn into a line of trees. Hedgelink has a wealth of information about managing hedges here: hedgelink.org.uk
Also the People’s Trust for Endangered Species have created an app specifically for landowners to assess their hedges and provide advice on how to manage each individual hedge; find out more and download it from here: https://hedgerowsurvey.ptes.org/healthy-hedgerows-survey
I hope that helps.
Tammy