I thought it right to finish what I started and conclude on this
After I emailed the dealership where I bought the car with my frustrations as to having this large bill so soon, their initial response was that BMW guidelines for AUC vehicles, is that if any work is required within 3000 miles OR 6 months, that this must be taken care of.
They then proceeded to provide the key fob reading from when they took the car in, highlighting the fact that I 'had clearly exceeded the 3000 miles required'.. however, the key reader they provided clearly stated that that the service items (Brake Fluid, Engine Oil, Air Filter Element, Spark Plugs and Microfilter) were due to expire in 10.2014 and since I bought the car end of April, this was within 6 months.
Once I pointed out that since it stated these Items were due within 6 months of me purchasing the car, which they knew about and were not disclosed to me (despite me enquiring about next due service, told 2016), then I feel like they were hidden from me with the safe bet that I would exceed the 3000 miles in these 6 months to make them liable (must be a small majority who do 6000 a year? I travel 5 miles to work and still exceed this) then they offered me a 30% contribution.
I said I would be happy to settle with a 50/50 contribution which they immediately agreed too.
I realise, by their sudden willingness to co-operate, that I maybe could have pushed harder (go to DP etc) and maybe got them to cover the whole cost, but I told myself I would have been happy with a contribution from the outset, I realise that the Brakes that need doing are not a service item and I should have been more on the ball when buying the car, so happy to draw a line under it, compromise and get the car in the shop.
Thank you for all the replies and advise, lessons definitely learnt!