The average monthly rent in the area is approximately £400 per person per month (roughly £92 per person per week). Regardless of this, some rents will fall above and below this price bracket. One and two bedroom properties in particular are often significantly higher in price. By looking at HouseSearch on a regular basis, hopefully you will be able to find a house within your budget.
Be wary of additional administrative charges and other fees, especially when going through Letting Agents.
Often in a shared house, students choose to split the rent to reflect the size and quality of the rooms each tenant has, so if you have a limited budget then you may want to consider discussing this with your friends and taking a smaller room at a lower rent.
It is also worth checking whether properties have any bills included in the rent price. This is unfortunately becoming less common, though some landlords will still include certain bills, especially water-rates and/or internet, in their rent.
If the rent is over the average £400 per month watermark then you will need to be sure that the property is worth paying more than the average for. If you are not sure, then look around at other similar properties to consider whether the price is truly reasonable for the type of accommodation being offered.