I am new to London and this is my first experience of tube strikes and need help to know which option is best getting from Clapham to King's Cross.

I need to get from Clapham to King's Cross Station tomorrow by 10:30 which would normally be easy by tube but the tube strikes have obviously ruined that. My options are walk, which will take 2 and a half hours, not ideal but I am fit enough if there's no other choice. Bus, but this will be unreliable as I know it will be busy and the traffic could be very bad at rush hour and still take at least an hour and a half. Or Thames Link train which should take an hour but I am scared that trains will be cancelled or full and I will be stuck.

Any experienced Londonders able to give advice on what is the best method?