I bought this calculator a fair while ago now- it must be about three years as I bought it for the start of my GCSEs as it was recommended as a good calculator for this stage of mathematics.
I think I paid around £12 at WHSmith for this calculator but I have heard that you can get it very cheap on the internet- I even heard of a friend that got it for £3 at some place on the world wide web! (Possibly ebay?)

This product is very compact and thin which makes it great for just slipping into your school bag and it has a slide on case which protects the screen..although I have actually lost this as you aren't allowed to take the case into official examinations in case you write some sort of equation on them or something? And I have misplaced it since then.
The buttons on the calculator are very easy to use, you don't need to press them too hard or stab at them to get them to work which is always a positive and they don't accidently press when you only touch them lightly which is also a good thing. The button faces are actually very ergonomic as your finger seems to fit onto them very nicely and they have a sort of 'soft touch' feel to them. The buttons themselves are mainly black or navy with bold white writing which are easily readable which is useful.

This calculator can carry out all the tasks that you will need for a GCSE Maths exam including standard form ( the X 10 to the power of x button) and basic trigonometry questions involving cos, tan and sin and also the inverse of these functions! Another REALLY great feature which is available on this calculator and not on some other similar models is the fact that you can easily convert decimals to fractions and vice versa by using the (S to D) button. This is so useful in exams and means that you don't have to remember what your fractions are in decimal forms (at least not for the calculator paper anyway...)
I reckon this calculator is pretty robust as I am quite rubbish at looking after my possessions and this is always rattling around in my bag and hasn't broken as of yet. However my brother also has one and has managed to break his screen by stabbing it with a compass... so as long as you don't do something stupid like that I am sure it will be fine!

All in all, this is a brilliant calculator for pre GCSE and GCSE maths as it includes everything you will need. If you are planning on going on to further level maths in A level or similar then I would recommend also getting a more complex (and unfortunately a lot more expensive) graphical calculator as there will be some useful functions on these type of calculators (like solving quadratic equation and drawing out graph transformations etc.) that you cannot do on the Casio fx-83EX. But even now, at university, i still keep this calculator as it is so easy to use and has useful functions that you sometimes don't even get on the very expensive calculators!
I would definitely recommend this product!

Another last note is to say that to be honest, you don't even need to bother with the instruction manual as it is so simple to use and it is a commonly used calculator in schools so the teachers are bound to know how to do everything!