Is it safe to ask this ONLINE person for help?

I applied to the university of Essax in the UK, and seeing that my family isn't living in the UK, and that I am under the age of 18, so I need to put a name as an emergency contact in the UK. I really don't know any friend or relative who is living there, and the only other way is to pay around 2000$ for some agency to "take care of me" and I am seriously not sure about joinin to that university, so it will be like payin 2000$ for nothing!! The only person whom I know is an old online friend, I used to call her my online mama, haha, so would it be safe to ask her if she can be my emergency contact JUST TO GET MY OFFER, because there is aBIG chance that i am not going any where there!