Assuming PCPartPicker part list / Price breakdown by merchant
i7-5820K, 32GB of DDR4 RAM, Quadro K4200.
All for £1826.
You can spend more on the CPU if you'd like (for a 5960X) or the GPU (for a Quadro K5000) and it'll still be less than 2500 pounds.
Feel free to spend more on the storage if you think it is necessary.
I would highly recommend you overclock the GPU for the best performance, but it's not a must by any means.