Chances are you'll never get hold of a 20th Anniversary PS4 given that they are going to be extremely limited. Indeed with only 12,300 being made worldwide, it seems likely that the UK will only have around 1000 and by the time some are given away in competitions and the like, then than doesn't really leave too many for Sony to sell to the consumer.
In this respect, the closest you'll probably get is by watching the video below, although you never know, maybe someone around here will be lucky, I know I'm going to do everything in my power to get hold of one.
So here's a little tease. Why do this to us Sony?