This is the problem that you have when you sign a tenancy agreement without physically seeing the property, you are bound under the terms of the tenancy which means that you would pay rent until the end of the term or until a new tenant takes of occupation.
If you simply walked out, it would depend whether the landlord decided to pursue you for that rent.
However it would appear that the landlord and the agent misrepresented the property by showing it is absolutely beautiful on the video well as the reality was something else.
On 1 October 2013, the Property Misdescriptions Act 1991 (PMA), which previously made it a criminal offence for estate agents to make false or misleading statements about properties being offered for sale, was repealed. The government has taken this step in order to reduce duplicate legislation because there are now two other pieces of legislation which regulate estate agents and other businesses involved in property sales and lettings: the Consumer Protection from Unfair Trading Regulations 2008 (CPRs) and the Business Protection from Misleading Marketing Regulations 2008 (BPRs)..
Why one is entitled unfair trading regulations and the other is misleading marketing regulations, I have no idea but it doesn’t affect the substance.
So you would have a counterclaim against the landlord and the agents for misrepresenting what you might want to tell them is that if they pursue you for this after you leave, you will be looking to substantial compensation under the above regulations. Tell them that the compensation is going to be far more than the outstanding rent.
It remains to be seen whether they accept that or whether they pursue you.
Thank you for letting me assist you with your legal question. I am glad that I was able to help.
I am not certain whether that answers the question for you or not, but I am happy to answer any specific points arising from this.
It will be my pleasure to help you again either further with this or any future questions you have