Do not sign up with Foxtons as you will sign with the devil. They are incompetent, arrogant, useless and are only interesting in one thing only money! As soon as they have your money and signature, they could not care less about you as a tenant and will create problems between you and the landlords. They also change your payment records and backdate rent increases so you end in rent arrears although you have paid your rent on time and in full at all times. They will harass you to leave the flat at the end of your contract so they can sign up new tenants and get a full commission, they hold your monies for weeks so your landlord thinks you have not paid your rent, they view flats without giving you 24 hours notice as required by law and will come at any moment with keys. They will phone you 20 times a day to push you to sign or let them in and invente false bids on both rentals and when buying a property.
My best and wisest advice ever - STAY AWAY or be prepared for a life in HELL!!!