Employee scheme and AVCs to PRSA

No - you can only access the PRSA AVC when retiring from the employment and taking benefits from the main occupational scheme.

You don't necessarily need to be retiring from the employment to take your benefits at Normal Retirement Age - that only applies to early retirements. But you do indeed need to take the AVCs or AVC PRSAs at the same time as the benefits from the main occupational pension scheme.