When you reach the M5 (this is Junction 29), turn onto it heading south, signed for Plymouth, and probably Torquay and Okehampton. Remain on the slip road as you will be leaving very shortly at the next exit (Junction 30).
Leave the M5 at Junction 30 - the Granada Services are signed off at this junction too,
Follow the slip-road down to a set of traffic lights. In fact there is a large roundabout under the M5 with traffic lights all round it.
Follow the lanes marked for Exeter, which should lead you off at the third exit onto a dual carriageway marked as the A379 and signposted to Exeter City Centre.
Signs now are for Exeter (sometimes City Centre too), and sometimes for Hospitals.
Take the third exit off this dual carriageway: this will lead you onto the old Exeter bypass, heading south.
Move into the right hand lane (of two) as soon as practicable.
You will reach Countess Weir roundabout, which also has traffic lights all around, and a pole in the middle with a TV camera on it (smile please!). There is also a Shell petrol station on the right before the roundabout.
Turn right - the third exit, signposted to Exeter City Centre. This is Topsham Road.
Look out for a high brick wall on the right with a (now disused) gate - this is the Barracks.
Turn right at lights into Barrack Road, signed to the main hospital (R D & E, Wonford).
At the first junction with lights, turn left, the Church is about 100 metres on your left (opposite the Nuffield Hospital) - you will see a white wall a little past the entrance.