based on your information, the position is as follows:
1. Under current legislation AVC funds can be invested in an ARF at retirement
2/3.Assuming your UK Scheme will transfer the value back to an Irish scheme (nor guaranteed), it really depends on the type of scheme as to whether these funds can subsequently be invested in an ARF on retirement. If the value is transferred into your existing employer scheme, then as things stand the money would have to be used to buy an annuity on retirement. If you can get the Transfer Value into a PRSA, then the ARF is possible.
4. Under current rules the maximum tax free lump sum on retirement is 150% of Final Salary (unless you are a 5%+ shareholder by then, in which case you can take up to 25% of the total fund). Assuming you take the max TFLS from the employer scheme, invest the AVC fund in an ARF, this will minimise the amount having to be invested into an annuity.
5. At retirement (assuming you are still an employee), all funds from occupational schemes are aggregated (incl AVCs). You max TFLS is 150% of Final Salary and the rest has be used to buy an annuity and/or invested into an ARF (again based on current legislation).
Hope this helps.
Conan