Sorted the issues with the HIDs, kit was short circuiting on some dodgy wiring from the previous owner. Luckily I have a sparky dad and he tidied everything up beautifully for me.
In regards to the brakes, turns out its not as bad as I initially thought. Only need a o/s caliper and pads both sides doing. £190 from local Vag dealer. Thank you for the offer of the A3 calipers, but id rather keep brakes standard at the moment :)
The car was only used on the weekends, so I hope that brake seizure was due to lack of use. Havent given it the full beans really yet as i dont want to do any further damage to the brakes, so going to enjoy hammering my foot in to the carpet when all is done :)