Growing any food crop in a greenhouse is a bit problematic since you are more less placing your plants into a vacuum, outside a natural environment. If a parasite gets in ... and it will ... they can ravage your plants rather quickly w/o your intervention since natural predators are likely not present.
Chemical treatments are problematic as well, you do not want to be spraying your plants all the time. Also, tea plants absorb any odors, chemical odors in a greenhouse can linger for quite some time.
You will need to consider temp control, heat in winter, cooling in other seasons. Humidity, too much or too little can be damaging and are often present in poorly planned greenhouses. Air circulation is a must.
Mechanical failure can be devastating. Losing your heat or electricity on a cold winter's night can kill off years and years of work.
Other than all that, have fun and go for it.