Loki Hi,
If you are interested I can propose the following setup which I use for my cars and those of friends and fellow members of the LR Club of Greece when they want to upgrade their solid front and rear brakes.
A pair of vented and drilled front brake disks.
A pair of spacers with seals and special bolts in order to convert the standard calipers so that they fit to the vented rotors and
A pair of solid but drilled rear brake disks.
This kit totally transforms the braking capabilities of a solid disks equipped Disco, RaRo or Defender.
Cost will be around 310 pounds including shipping to your door.
Alternatively if you are NOT interested for the front vented and drilled and rear drilled brake disks but you are only looking for the calipers upgrade kit (spacers, seals and bolts) this will be 55 pounds delivered to your door.
(yes I know you are in the UK and I am in Greece)
Take care