Bit of a problem here mate. It appears over that last few years that the only chance of getting white freestyle tyres in the UK are of you shell out on Panaracers or Haro etc.
There were a couple of sources in the US that even with postage costs were still cheaper.
Sadly though one type (Panaracers copies) were sold by Rini's and unfortunately their owner Virginia has passed on, and as far as I'm aware they are no longer trading.
The others were from Porkchop, (comp ST) copies by Duro, and he's sold out.