Offshore FO's salaries start between £55,000 and £68,000 and top out at just a touch over £90,000 for senior SFO's.
Captain salaries start at around £100,000 and top out at ~£140,000 for the highest band of captains at certain companies
Offshore operators will generally match roughly 9% for pensions. Most have private medical insurance, and also loss of license insurance.
Onshore, I have seen salaries ranging from £45,000 - £105,00 depending on industry.