thank you. the most obvious concerns in relation to this agreement flow from the request that rent is paid upfront for the entire year. whilst this is a lawful request, it presents significant risks from your friend's point of view. In no particular order, these are as follows:
1) presumably, your friend has no assurance that the purported landlord owns the property and as such, your friend could potentially find that the landlord is letting the property unlawfully and they could find themselves addicted before the end of the term.
2) the landlord as a limited liability partnership as such, if the above were the case, or if the landlord became insolvent - after all, your friend presumably knows little or nothing of the landlord's financial position - then they would again potentially find themselves being forced to leave the property early due to the above or due to landlord insolvency or mortgage repossession with little or no means to recover the rent they have paid;
3) one way to address at least some of the above risks is for the agents to provide evidence of a propertymark client money protection insurance policy currently in force AND to include a provision in the tenancy agreement that they will hold the rent as "stakeholder" and only pay it to the landlord as it falls due. In this way, it would ensure that the agent holds onto the money and only releases the rent monthly as it falls due to the landlord and your friend would have the benefit of a client protection insurance policy to protect against the risk of the agent becoming insolvent.
in summary, the main risk is that your friend is essentially being asked to hand over a relatively large sum of money to an entity it knows nothing about. Everything may be fine but trusting this to fate could leave your friend significantly out of pocket if any of the above risks or potentially another risk occurs.