An ARF is a vehicle into which you can transfer funds from either a Personal Pension Plan or an Executive Pension Plan (subject to being a 5%+ shareholder) on retirement. An ARF is not a pension accumulation product (such as a Personal Pension Plan or an Executive Pension Plan). Tax relief applies to contributions invested into a Personal Pension or an Executive Pension, but one cannot invest regulat contributions into an ARF.
Any funds transferred into an ARF on retirement (after taking the tax-free lump sum) does not itself qualify for any additional tax relief. Drawdowns taken from the ARF are taxable as income in the normal way (just like a pension/annuity income).