We are looking for self-catering accommodation in London and have found an interesting option with www.heartoflondon.com - anyone familiar with this agency? Thanks!
I have not personally used this site, but you can ask for references, and read the fine print before renting.
For example: ask about cancelation policy, security deposit fee, your UK contact person, how you'll get the key, and what is part of your apartment.
Most rental places advertise in other sites, such as vrbo, etc.
Have a great time... I rented an apartment and loved it!