The question is not about whether renting is lawful or not. The question is about the terms and conditions that come in every rental contract, and these are:
If the rent remains unpaid for over 14 days than its due date then an interest rate of 4% will be added to the due amount every additional day
A deposit must be paid, the deposit is stored in a bank protected by a government scheme, while the deposit is in the bank it will start to accumulate interest, once the deposit is to be given back to you then the interest is also returned either to you or the landlord.
Both of these two terms are enforced by the government and might be part of every law binding contract.
Now the question is this considered Riba, and what alternatives does one have available?
Muslim (1598) narrated that Jaabir said: The Messenger of Allah (blessings and peace of Allah be upon him) cursed the one who consumes riba and the one who pays it, the one who writes it down and the two who witness it, and he said: they are all the same.
Assured shorthold tenancies (ASTs) is the type of a tenancy agreement and in the Standard Clauses in Assured Shorthold Tenancy Agreements you'll find mention of the terms quoted above.