The settlement offer was introduced by s111A of the Employment Rights Act 1996 to provide a new tool to assist employers to resolve issues at work. The offer and the subsequent discussions between the employer and the employee can result in them concluding a settlement agreement by which the employment is terminated in a mutually acceptable way.
FATCA (Foreign Account Tax Compliance Act) is an American provision enacted in March 2010 and aimed at foreign financial institutions. It is part of a larger piece of legislation: Hiring Incentives to Restore Employment Act, designed to ensure that American citizens are fully disclosing their worldwide income to the US Internal Revenue Service.
A list of most relevant HMRC links that includes:How to fill in your tax return, residence, remittance basis etc. notes,Capital gains summary notes, UK property notes, Additional information notes, and many more
HMRC has had a change of policy following the First Tier Tribunal (FTT) decision in Robinson Family Ltd  UKFTT 360 (TC). The changes are three-fold and are discussed here policy change by policy change.