Some of this will depend on your attitude toward the MBA. If you're resigned to get a new one, then the existing one is essentially scrap. Which is to say, a candidate for experimentation.
First you will need to get out any contaminants - in this case the tea, milk, and sugar. Many manufacturers use pure water to wash system components - they used to use harsh chemicals, but now water. But, batteries, speakers, displays, and disk drives don't like water. So you could try this: take off bottom cover and remove battery and mSATA SSD drive, and set aside. Go to pharmacy and get pure (distilled) water. Rinse keyboard and motherboard, taking care to key away from components that may not like this, such as water. Separately, rinse battery and drive. Use contact cleaner on connections for these.
Air dry, or in oven @150 degrees F for a few hours. (Our oven doesn't go that low, but my wife reminded me that there is a bread-proofing setting, which is a little lower.)
In my experience, we had the same iPhone 4 go into soapy dishwater and 6 months later into the toilet. Both time we turned it off immediately, put into bowl of rice, put in oven. Then put on charger after 24-36 hours. Still works great.
A friend spilled Coke (not diet, so sugary) into a MacBook. He considered it toast, so had no problem trying the experiment: rinse, turn upside down to drain, and hair dryer for 30 minutes. It didn't work. But two weeks later he plugged it in, and it came back to life. That was 2 years ago and still works fine. YMMV.