What will my tax be when renting my property (links to Tax Calculators appreciated)

gcpbuyer

Hi there - reluctant landlord here - I moved in with my partner and now renting out my flat. 

I've been looking online and various landlord tax calculators have been giving me different figures. Just wondering if anyone here can help me figure this out, or point me in the direction of a decent landlord tax calculator. 

Personal details: 
My base salary: £90,000
Bonus: £15,300 (before tax)
Company stocks: £7,900 ( before tax, this is 1/3 of my total allocation, which vests every 3 years)

Rental details:
Rental income per year: £25,800
Service charge+expenses: £3,000
Interest on mortgage: £255

Any idea what what my tax bill will be for the rental property? A link to a decent calculator would be great as well. Thanks