It will depend on which country you become resident in as to where the pension is declared. Some countries will give full relief even for government pensions. Guidance by country can be found here:
Digest of Double Taxation Treaties
As a UK national you will still be entitled to your personal allowance regardless of where you are tax resident.
You can still transfer marriage allowance even if you are non resident.
The rates of tax on any UK income will be based on your last place of residence, Scotland.
If you have no UK income other than the pensions then you will not need to complete a Self Assessment tax return. Criteria for completion of a return can be found here:
Self Assessment tax returns
If you sell your house within 9 months of it no longer being your main residence then you will not need to report anything for capital gains. You only need to report for captal gains if it is a taxable capital gain.
Tell HMRC about Capital Gains Tax on UK property or land if you’re non-resident
UK interest and dividends will still attract the savings and dividend allowance, however, as a non resident these would not be reported to the UK.