You may find it useful to search various websites:
It may also be worth looking out for postcards in newsagents & shop windows and searching through www.gumtree.co.uk - do beware when searching through these means, if they comply with legal regulations then they should be okay to live in.
Make sure the landlord / letting agent is registered: if you've found a property you're keen to move in to, do a landlord registration search to make sure the landlord of the property you're looking to rent is registered to the council, as this is a legal requirement for all landlords.
Think about Council Tax.
You will have to pay a deposit: you will normally be required to pay a deposit and possibly the 1st months rent installment prior to moving to the property. The deposit should only be the same as the 1st months rent, if it is more, then you should question this with your landlord / letting agent.