Try the "foreign" aisle of your local supermarket - if they have "english" delicacies you may find packaged loose tea. Twinings is excellent, but there are many other good brands. Or try googling Twinings and checking their website
There's a small specialty shop near me that sells fresh spices as well as loose teas. You can't actually "shop" online for their goods because the site isn't fully functional, but you can look at what they carry & then use her "Contact Us" page to inquire about prices etc. http://www.thespicesmuggler.com/
I order from adagio teas. They have some really nice loose teas and tea bags. I also have that cool tea pot on the front page - the IngenuiTEA - love it!