Have been paying into a work pension scheme and part of the of the employee contributions go towards AVCs. Could be mistaken but thought i heard recently that there is extra tax relief that can be claimed back on these?
Pension contributions (including AVCs) through payroll already attract tax relief at source.
As opposed to a lump sum AVC paid separately from net income, where you'd have to claim tax relief separately.
The net tax position is the same whichever way you pay your AVC, and you are still getting the full tax relief by doing it through payroll (barring any errors by your employer).