By Car Not advisable unless you know London well. There is a car park in nearby Curzon Street, but it is expensive and the roads can be congested.
Public transport is very good and a much less stressful way to get around London.
The distance is approximately 15 miles, and the journey should take about 45 minutes, but London's traffic can be very variable and it could take much longer in the rush hour. Once at Paddington, change to the Underground and take the Bakerloo Line eastwards to Baker Street. Here, change to the Jubilee Line and journey southwards to Green Park. The journey time is about 30 minutes. From Victoria, change to the Underground and take the Victoria Line northwards to Green Park.