Hi Mario,
Shouldn't there be a subtle difference between Delivery and Truck? As I understand it, Truck should allow routing THROUGH an area, whereas Delivery should also allow routing INTO an area. Each allowing or denying routing conforming to the UK motoring restriction 'HGV - Access only'. I can think of many instances where hgvs are only allowed into a road network if they are delivering or gaining access to a property, but not if they're driving through.
The Garmin access restrictions as we understand them are not as flexible as the OSM tags. No through routing only works for cars, i.e. you can have motorcar=destination but the more general case access=destination or other specific cases like hgv=destination don't work. Cheers, Mark