In all honesty, everything was perfect. Perfectly located (close to public transport, supermarkets and catford 'centre' were a max 5min walk away too, etc). If you have trouble sleeping, take some earplugs with you as there are ambulances passing the place everyday, it didn't bother us as we were prepared for this.
The airbnb itself was super clean, and everything we might need was basically already available, think of: cooking materials (herbs, spices, oils), some tupperware, stuff like tinfoil, soap, toiletpaper, paper towels, some info papers about the tube, etc.
Checking in went smooth as there was a guide provided before checking in. For some reason I just tried to open flat 20 instead flat 9, but I got an immediate response from Catriona, so checking in took me about 5min tops.
Catriona was super friendly and helpful, the overall communication was perfect, it said 'responses take about an hour', but most of the time you already got a response within an hour!
It was an amazing stay and I'd definitely recommend this airbnb to anyone that wants to stay in/near London!