You can also drive untaxed to a pre-arranged IVA test...
'the only circumstances in which you can drive the vehicle before completing the registrationand licensing formalities are to and from a pre-arranged IVA and/or MoT test and to and from a garagefor remedial work following failure to pass the inspection. Other than in these situations, the vehicle
must not be used on the road until the licensing and registration formalities have been completed.'