Going to a graduation- What should I wear?

I'm going to my cousins university graduation later this month. I am in the UK (not sure if graduations are different depending on the location) and the weather is meant to be quite hot and sunny on the day. I have never been to a graduation, so I am not sure really what to expect, and what outfit to wear. I have three outfits to choose between- I am not sure which to wear as I don't want to look over the top or like I haven't bothered.
Here are the links to the pictures of my outfit (please ignore the awkward poses and how tired I look):

https://mail-attachment.googleusercontent.com/attachment/?ui=2&ik=556c3ca7a6&view=att&th=13f9fe6015c178ef&attid=0.1&disp=inline&realattid=f_hin7zrnd0&safe=1&zw&saduie=AG9B_P-vi5USU4UT2GMtgp9MXua5&sadet=1372777249672&sads=hgcfGNUoH3zVdXq-4tjUHkym0yU

https://mail-attachment.googleusercontent.com/attachment/?ui=2&ik=556c3ca7a6&view=att&th=13f9fe6015c178ef&attid=0.2&disp=inline&realattid=f_hin7zrrm1&safe=1&zw&saduie=AG9B_P-vi5USU4UT2GMtgp9MXua5&sadet=1372777265069&sads=QfEDPi9cFn5zp2juOL8bDdXIjcI

https://mail-attachment.googleusercontent.com/attachment/?ui=2&ik=556c3ca7a6&view=att&th=13f9fe6015c178ef&attid=0.3&disp=inline&realattid=f_hin7zrti2&safe=1&zw&saduie=AG9B_P-vi5USU4UT2GMtgp9MXua5&sadet=1372777275453&sads=R2cZjz5xY5mpb7u7BwVFqhZyLkw

Thanks guys :)
I can't open the links on my phone but it depends on your age if you are around 13/14/15/16 I would go for maybe a dress from river island or American apparel although it is very expensive! Maybe try primark even some of the cheaper high street shops have nice fashionable clothes! Maybe a nice tight maxi dress/midi dress a denim jacket from primark and a pair of fashionable runners like Adidas nizzas or Nike blazers or puma suedes! Sounds tacky but all together they can look really nice! Even a pair of Capri leggings , a fancy top and a cardigan along with sandals or runners can look very nice!
Tag: Going to a graduation- What should I wear?