Cleo's place is one block off Las Ramblas and within ten minutes walk of the metro station. Take L3 to the university area and transfer to L9 to the airport. The cost is 4.60 Euro. It takes approximately 1 hour on the metro to reach the airport.
Cleo has put together a nice book of local information. He was accommodating and let us come early. Cleo took all the time needed to explain things in the apartment and answer our questions about Barcelona. Plus he was available by messaging during our visit.
The one thing visitors need to be aware of is that the apartment is up two flights of stairs. There is no elevator, so pack accordingly.
We would stay at Cleo's again.