You can (and, I think, must) draw down your old pension at 65, if this is the preserved age attached to it. Abatement (as I understand it) would only apply if the total combined amount of this pension plus your new (current) public service salary exceeds the current salary attached to your old job. Example at 65 :
-New public service job salary = €40000
- Annual Pension(old) at 65 = €8000
- Total = €48000
If the current salary attached to your old job is now €50000, then no abatement applies. However, if it is €45000, then there will be an abatement to limit the total amount in payment to you to this figure. Abatement would cease at 68. (I am assuming that the combined total of your public service years will not exceed 40). As far as I know, the lump sum is not affected.
I take it you did not resign your original job under one of the Incentivised Early retirement Schemes. If so, I think further restrictions apply.
Going back to to your original query. If your AVC fund is specifically linked to your original job/pension scheme then I assume that you can draw it down when this pension becomes payable, ie, at 65. Maybe you should check again with your Pension Adviser - I suspect many of them may not be familiar with this relatively new scenario (ie two separate public service schemes/pensions).
I should say again that this is my reading of the documentation - I have no experience of the new scheme or the application of abatement. Someone else here may be able to clarify.