Moadweeb– Sorry I don’t not have any good recommends for you as I usually stay in the Hammersmith/Chiswick area.
Carajillo2Sugar– It totally depends on the property you choose to stay in. Sometimes they could be the owners 2nd home that they strictly rent out to ABnB users. Other times like most of my stays, it is a private room in someones flat or house. It is up to you if you choose to interact with the host, and they respect your time and privacy to the utmost.
You will certainly be presented with a key to enter the building as well as one to your own room upon arrival along with a welcome pack like other posters have mentioned above. As for the contact details, most good hosts will have their cell or email verified for contact throughout the process.
The biggest issue Air BnB will still has to overcome is the service aspect. Something I have read already from posters here… If your expecting the typical hotel experience with full service, food, ect this is not for you. If your looking to save serious money while still being feet away from the city you traveled to then I would recommend it.
*Please note, I do not work for, or have any reason to recommend A Bnb for any other reason than I have had wonderful experiences using them as a service and hope others can too!