partial deposits

Tenancy Deposits

I have a six bedroom student let house, which one existing tenant and five new tenants have signed for - on a one year AST from July 2010 ( I have yet to sign as I explained to the group I will not sign until all the relevant documents have been returned - guarantor standing order and a full deposit of £1800.00 )

I have so far received £1500.00 from five of the tenants the sixth one promising to have paid the deposit into my account by today. The sixth tenant has not paid as yet and it is now 14 days (tonight) since they signed and the first part of the deposit was received 3 days later.

My question is: Am I within my legal right to not register the deposit until the final £300 is received and treat this as a holding fee until such time or: refund the deposits (minus an admin fee) and find a new group or: give the existing group a chance to find a replacement suitable tenant for the time wasting tenant.

Thanks