Just get the train down to Southampton parkway (from Waterloo if going via London) and jump on the free shuttle bus. When I LEFT the centre after the test last week they were running every '15 min but that was 4-4.30pm'ish. Early morning before 8am I could not advise you.
Give them a quick call to confirm.
Corporate and Technical Centre
4000 Parkway
Whiteley
Fareham
Hants PO15 7FL
General Enquiries: 01489 616001
HR Enquiries: 01489 616090