Lindsay Lohan -- Clubbing and Partying In London -- For Big Bucks

Recovering addict Lindsay Lohan is taking steps to ensure she stays clean and sober ... she's put herself up for hire to spend evenings in bars and nightclubs.

Sarcasm aside -- we've learned LiLo has hooked up with some Londoners with connections to the city's hottest clubs and other night spots ... and they've negotiated deals for her to make tens of thousands of dollars in appearance fees.

We're told Lindsay has already made some appearances and more are scheduled ... she's pulling in between $5K - $15K per appearance.

She claims she's stone cold sober ... in the middle of these boozefests.

So Oprah, looks like she took your advice, right?