What data protection (GDPR) consent do we need to get from clients when we use OVForm?

GDPR may be covered by your practice privacy policy - does it allow you to share client details with third parties e.g. labs, pet crematoriums, debt collectors etc? If so then no worries. 

If in doubt then probably best to ask. 

If you send out a form pre appointment to get the info for the AHC you can mention that you are using OVForm.