This means that are claiming them in line 6 (or in line 5) of Anlage Vorsorgeaufwand, since UK NI contributions are tax-deductible.
And you will be sending your Finanzamt proof for your UK NI contributions.
--> then please also take care to check that the Finanzamt really did consider them in the Bescheid.
The problem is that if the caseworker at the Finanzamt is sloppy, he/she will simply query the Finanzamt database for the German social security contributions, which will overwrite the values from your filed tax return, i.e. will delete your UK NI contributions and will then not make a second pass through the tax return to also manually fill in the non-German contributions you had claimed for.