I don't know how contesting it would work. You can't prove a negative, i.e. that weed wasn't there, and even if they re-inspect, they'll just assume you moved/sold/smoked it to hide evidence.

I don't know how UK housing laws work, but call the council or the equivalent to discuss this, don't ask /adv/.

Unless you have a history of anti-social behaviour or they have proof you were growing to supply, they won't be able to touch you. It's likely that if they take any action, it'll be a notice or a warning and then the housing officer from your area will watch you like a hawk to a few months.

I work in this field and we have let people stay in houses for much worse.

Just be more careful in future and don't piss your neighbours off, you filthy pothead.

If all else fails you'll have a clean test after 2 weeks if you need it, besides that they can't throw you out for smell.

There is perfume that smells like weed, if you're clean you should be fine but if you live in a complex be so thoughtful and smoke while going for a walk and come back not smelly.