I can speak only as a US/UK citizen who moved back to the UK and I see from an earlier post of yours that your husband is also a USC.
For me my US private pensions and withdrawals from my IRA are taxable in the UK, but Roth conversions are only taxable in the US
Surprisingly, SS is only taxable in the UK.
Roth withdrawals are tax free in both countries.
OK so if the husband is a US citizen then US law means that all the pensions that the OP mentions except the ROTH are taxable in the US. If the OP applies the treaty then the SS would become US tax free. So here's a summary for a USC resident in the UK with the treaty applied.
1) Qualified DB pension taxed in UK and US, resourced to UK so you can get FTC
2) Non-qualified DB pension taxed in UK and US, resourced to UK so you can get FTC. I'd ask a professional whether the treaty applies to non-qualified plans and whether HMRC recognizes the tax deferral wrapper.
3) NQDC taxed in UK and US, resourced to UK so you can get FTC. I'd ask a professional whether the treaty applies to non-qualified plans and whether HMRC recognizes the tax deferral wrapper.
4) SS taxable only in UK
5) IRA withdrawals taxed in UK and US, resourced to UK so you can get FTC
6) ROTH are tax free in both US and the UK.
As you husband is a US citizen the administrators will apply withholding and after UK tax is paid you'll have to file US taxes and get credit for the UK tax and the withholding.