Maybe a little search on here? I am sure you will get loads of ideas. My tutor put me in touch with Ellisons and once I started looking on here I came across loads of names. Also Google for beauty suppliers, it is free to register and you can compare prices at your leisure then, they also always e-mail special offers through so you never miss out on saving a few pennies. Of course there is Capitol Hair and Beauty and Salon Services/Sally's you would need to register with both showing proof of Qualifications or apply for a student card, again proving that you are currently in training to be able to purchase at trade prices.
Hope this helps