use this one
https://www.mrcentralheating.co.uk/btu-calculator
also using this info
http://www.directheatingsupplies.co.uk/news/btu-calculator-how-to-work-out-what-radiator-you-need/
so using the above get your desired btu then using the other add or delete
For solid floor -10%
the other calculator only calculates room size and if its sheltered or exposed it dosnt include window sizes
go here for size of rads most places stock stelrad including ebay
http://www.directheatingsupplies.co.uk/stelrad-vita-compact-radiators
Nice one, will give it another bash later. Do I need to add the BTU requirement of hot water too?