Plenty of scope for AVC contributions even if you'll have 40 years including the following:
Revenue max is 2/3 final salary. The standard PS pension (max) of 3/2 final salary lump sum and 1/2 final salary pension means that you are commuting 1/6 final salary for the lump sum. Given annuity rates etc., Revenue accept that this commutation factor is acting against the interest of the pensioner and they will allow AVC contribution to give you the full benefit of the tax-free provision that would be available were there no commutation.
Spouses and children provision is less than permitted by Revenue. As a simple example, on your death (with no dependent children) your spouse would only receive 1/2 of your pension. The Revenue limit is a surviving spouse pension equal to that of the deceased pensioner.
Have you non-pensionable earnings? These would provide scope for tax-relieved AVC contribution.
Whether there is any point in AVC contribution in your particular case (i.e. your question), that's a separate issue altogether. But there is undoubtedly scope.