I got both at my early scan. I was 7+ weeks, baby appears on abdominal ultrasound, but still did a transvag to get a better look at the HB.
Nice big full bladder for abdominal scan, empty bladder for transvag.
Id say at 8w its very likely they will try abdominal first. If not then they may suggest returning later. Alot of clinics take after the 8w mark though to ensure you see something via abdominal ultrasound by this point.
Good luck!
xxxx