Hi Imre de Daranyi,
This is a forum for general queries so I would not be able to give you a definite yes or no on your personal circumstances, however you may be able to claim a basic rate 20% tax reduction to the lower of your finance costs, property business profits or adjusted total income.
Guidance can be found at
Tax relief for residential landlords: how it's worked out the finance costs (not your full mortgage payment) should be entered in to the box ’Residential property finance costs’ in the UK property income section of your tax return, if you are completing a paper tax return this is on page UKP2 of the SA105 box number 44.
Thank you.