Any camera in that price range should have as many pixels as your daughter is ever likely to need. Likewise, any reputable brand should have a fairly good quality lens, with enough shooting options for a casual user. That only leaves seeking a decent optical zoom feature. Very few cameras offer greater than 5x but this one has an 8x zoom:
http://www.argos.co.uk/static/Product/partNumber/5597082.htm
It's got really good reviews (click the link to read them) and it's also available in black:
http://www.argos.co.uk/static/Product/partNumber/5597075.htm
... But keep in mind that it's not likely to have a memory card as part of the price. The store will try to sell you one from in-house and it's probably going to be near half of what you're expecting to pay for the camera alone. If you go on-line or to discount stores you can find the same card of a lot less. Here in the U.S. the brand of choice seems to be Sandisk.
An 8GB card that fits most sameras with a standard Secure Digital High Capacity (SDHC) Class 10 card is discounted right now for $8.99 (U.S.) down from the usual $25... so shop around...
Also you will need to buy rechargable batteries and a charger as the batteries supplied may only last about 2 hours.
In fact if you get a camera that takes 4 x AA batteries that would be better, or maybe a Lithium Ion barry which will last even longer (then you dont need to buy rechargable batteries so can add it to the price of the camera).
It is 10 megapixel but dont get hung up on megapixels. A 14mp may take worse pictures that a 10mp as it may be they are trying to squeeze too many MP on the camera.