London to North Oxford and Polstead Road

Head out of London on Westway to the Polish War Memorial and M40 (Oxford and Birmingham).

The motorway goes through the Chiltern Hills, past High Wycombe, and then comes down through a cutting into the upper Thames valley with a magnificent view of Didcot Power Station, and Brunel's Billiard Table stretching into the far distance.

About 5 miles after that is the turn-off for Oxford, which you take.

After another 4 or 5 miles, you reach the Headington Roundabout on the Oxford Ring Road.  City centre is straight on, but instead you turn right - i.e. going anticlockwise around the ring road (probably marked A40 Witney and Cheltenham).

You are now on the Oxford North-Eastern bypass, an early (1930s) example of integrated urban traffic management with cycle track although many cyclists resisted the notion, see The Thinking Cyclist

At the next roundabout (after 2 or 3 miles), you turn left - i.e. heading into the city.

You are now going South down the Banbury Road.

After less than a mile, the Banbury Road passes through a shopping district ~ Summertown;  when the shops thin out and start to be replaced by North Oxford gothic, start looking out for the street names you pass on the left,

Belbroughton Road is bonny,
and pinkly bursts the spray

   Marston Ferry Rd (at a traffic light)
   Belbroughton Rd (at a pedestrian traffic light)
   Linton Rd

Immediately after passing Linton Rd on your left, turn right off the Banbury Road into Rawlinson Road; at the end of Rawlinson Road, turn left into Woodstock Road and immediately right into Polstead RoadSt Margaret's Institute is at the far end of Polstead Road on the right, just before the pub on the corner.  The door to the Playroom is in the passageway along the right hand side of the building.