It shouldn't make any difference if you're operating freelance/mobile. As far as I know, you can purchase it from either of the two wholesalers, Aston & Fincher or Star Qualities in the UK. You will just need to register with them. When I used to buy products from Aston & Fincher in the UK, I think I had to show them copies of my insurance details rather than certificates.
Why not give them a call tomorrow?
I buy mine from Flair.ie in Ireland and I just had to show my certs to register with them. I can also order from them online.
I recommend you try the stylists travel pack initially.