Foreign Tax Credit Relief

Can someone please confirm my understanding of this please?

Tax payer has Australian employment income of £25k which has been taxed significantly in Australia.

UK Income is rental income £4k and dividends £19k.  Without foreign employment income no UK tax due as not hitting higher rates.  If add in employment income will be tax on dividends in higher rate so can I claim FTCR on the additional tax due?

Guidance says FTCR is lower of foreign tax paid and additional tax due on this source of income but as dividends always top slice is this correct?

Thanks