tachograph:
As far as I’m aware you cannot do a DCPC course without having HGV/PCV entitlement, so if you’re over 70 you will not have HGV entitlement and will have to do the HGV medical in order to renew your HGV entitlement before being able to do the DCPC courses.
I make it that you’re spot-on too tachograph.
Last year my partner, who has a pre '97 car licence hit 70, so she received an option to have a medical if she wished to retain her C1 entitlement.
She declined the offer, but still had to send her licence to DVLA for them to renew her B entitlement.
When her licence came back, the C1 entitlement had magically disappeared.