OK, on the compressor side, I strongly suggest you consider the Buzz Audio SOC1.1
Awesome stereo compressor and Atlas currently has them for $1899. SoundOnSound review at
For a preamp, considering your "Brit Rock" style, I would think that the Chandler TG-2 would suit you down to the ground.
Atlas has these for $1730 with the PSU.A pre amp from the same rare series used on many classic Abbey Road recordings. This pre features the same discrete transformer balanced sound and amplifier stages as the limiter and offers a warm smooth tone with a surprisingly open, clear top end (dare I say a nicer top than a Neve module).
This gives you 2 awesome channels for under your $4k limit