It was great staying at Wills apt which was clean and quiet as advertised. The place is well maintained and stuffs are organized! It is well located, 2 min walk to the nearest bus stop and from there I could get to Piccadilly in about 20mins via fancy neighborhoods like Sloan Sq and Knightsbridge. There is a bicycle docking station nearby as well - 2 mins. Biking along the river up to Big Ben was a great start. Wills is very friendly, he gave me clear direction how to get to his place via whatsapp and email and he picked me up at the World Ends bus stop. He was kind enough to take me to have fish and chips that only local folks know about! Besides the tender and crispy cod fish, banana fritters and stem ginger ice cream were also yummy. I came to London with no specific itinerary but Wills made excellent recommendations on what to do in 3 days.
From Heathrow, it took about 1.5 hours in subway and bus to get to the flat. So on your way back to the airport, do plan ahead if you have to get tax refund at the airport.