Try
http://www.hostelworld.com
Don't be put off by the word 'hostel' in that address. Just click where it says 'Additional search options'. This enables you to place check marks alongside 'Budget hotels' and 'Guesthouses'. You can also specify things like 'breakfast included' and get the prices quoted in sterling.
You'll find dozens of hotels listed within your price range. Some hotels have a 'customer satisfaction' rating, as a percentage, alongside them. This is only present when at least 10 people have submitted reviews within the past 6 months but it doesn't mean that the other hotels don't have customer reviews available. (For all of the the hotels, irrespective of whether an average score is present, you can access all of the reviews available by clicking on the 'Ratings' tab on the page which gives the hotel's details).
There are dozens of possible places for you to consider but my eye was drawn to the 'Night & Day Guest House' which, at 94%, has the highest customer satisfaction rating I've ever seen on that website. It does have the disadvantage of a shared bathroom but it's just within your budget at �24.02 per person per night, including breakfast. (I looked at some random dates in May). However, if that's not to your liking, there are lots of others.
Chris