120k in the U.K. is achievable but as 212 said it would be a senior captain with TRE or Chief Pilot attached to their email signature.
For a new joiner to any of the offshore companies carrying over seniority could be difficult so in today's market those earning 120k+ would be fairly senior captains in the company.
Jumping ship to a different company could be difficult to earn that unless you get a special deal or sell your soul to go to the Shetlands or Outer Hebrides!