Check your contract for a clause that allows you to leave. Most contracts are fixed term agreements and do not have a clause that allows you to leave.
This means you cannot unilaterally end the contract. If you believe your landlord is breaching the contract this does not mean you can also breach it! If you believe your landlord is breaching the contract (and you have exhausted all other methods to deal with it) you could take your landlord to court.
But by the same token, if you breach your contract you could be putting yourself at risk of court action too. If the landlord is breaching the contract speak to your legal advisor about monies.
Most landlords will let people leave if they find a replacement tenant. If you are in a joint contract the other tenants have the right to refuse a replacement but should only do so on reasonable grounds (such as council tax liability) and you should notify the landlord if they are being obstructive. If you are on an individual contract you do not need permission of the rest of the household.
If you are housed by the university, a larger supplier or a landlord with a large number of properties, you may be able to transfer to a different room or property in their portfolio. This way there is no loss of income to the owner and you get to move away from the problem.
If there is a price differences try to work out costs and liabilities before moving with the landlord so there are no nasty surprises financially.