The Tenancy Deposit Scheme applies to Assured Shortholds, and from my understanding, if you have a live-in landlord, then your type of let does not fall under this category, and therefore the tenancy deposit scheme requirements may not apply.
From the CAB:
http://www.adviceguide.org.uk/england/housing_e/housing_fact_sheets.htm, the pdf on Tenancy Deposits states the following:(Emphasis mine)
This fact sheet is for people starting a new tenancy with a private landlord or letting agent from 6 April 2007. It only applies to assured shorthold tenants. Most new private tenancies are likely to be assured shorthold, unless your landlord lives with you or your accommodation goes with your job. If you are unsure about what kind of tenancy you are starting, you should get advice.
Here's a load of information from the CAB regarding
Renting from a private landlord, which appears to be a bit more relevant in your case than the TDS.
Also, Your landlady also might not know how much your share of the bills is for a while--some companies only send bills every 3 months! So, when in doubt, I'd recommend checking with your local Citizens Advice Bureau, as they may be able to offer additional insight into your specific situation.