Don't think so.
Without removing the headlining to check, I'd bet that the connector on the antenna base is FAKRA (every recent Vauxhall I've had the pleasure of replacing the antenna on has been FAKRA)
The item listed has DIN. You'd need a DIN to FAKRA converting lead to power the shark fin replacment (FAKRA connectors send the power for the amp up the inner conductor of the cable).
Not sure how good it'll be at receiving Band III DAB
The cases where the GPS hasn't worked and the radio signal has been poor is because the wires were the wrong way round, both the cables I'm sure go to the same place. My Astra that has just gone back I'm sure was there. Also the GPS receiver needs to have a direct line of sight to thesatellites, it can't do that if it's buried behind the dashboard.