What makes you think its a lambda sensor problem ?

no idea really, was easy to get to

Did you have the fault codes read out ?

err take it i need some sort of equipment, so nope

As the dash light is on, I suspect it is another sensor problem.

Dont guess, get the codes read and save yourself time and effort
replacing parts you probally wont need

just trying basic stuff, with limited knowledge before the other half takes it to fords in the morning