Watch head yes, but it's not a cheap process for an assembled watch. Bracelets are difficult and very expensive. It's all very much cheaper when done to batches of new components prior to initial assembly.
Cost depends a lot on the condition of the watch and how much prep work is needed before sending for coating, but if you figure a couple of hundred pounds, that would cover most cases. That would include;
P&P to the UK case re-finisher
Total disassembly of the watch
Case prep work and re-finishing
Pre-coating super cleanse (case must be totally free of any contaminants)
Shipping to and from the coaters (all of the better labs are outside of the UK)
DLC Coating
Complete reassembly of the watch when back at the UK re-finisher.
Testing after re-assembly
P&P back to you.