This image may help you with this step. Please let me know your results Alice :)
If this doesn't help, another suggestion would be for you to take your iPad in a very dark enviroment, perhaps at night in bed, and just see if the display is a little easier to view in complete darkness. If so, try my suggestion in my original response to alter the brightness settings.
If neither of these 2 methods are successful then on futher research your screen and backlight may have developed a fault and you would need to take your iPad into an Apple Store.
A list of all stores in the UK can be found here - http://www.apple.com/uk/retail/storelist/
In each store is a Genius bar where friendly staff if possible will replace your screen and sometimes even your iPad. I would suggest backing up your iPad through itunes if this is something you end up doing so that you can easily sync all your files, apps etc back to normal :)
I hope my response helps you to fix the problem you are facing with your iPad. Please let me know how everything goes.
If there is anything more you may need help with please do not hesistate to respond to this answer. If you were happy with my help, please would you take a moment to rate my answer with a score between 3 and 5.
Thank you very much, and all the best Alice!