Accepting Conditional then Declining Unconditional offer

Hey guys, so I got two conditional offers from two university in london. My agent wants me to accept the offer and the university ask to respond within 16 days. But I’m not sure if I want to go there as I am waiting for other applications and haven’t made a firm choice. So my question is:
Can I accept the conditional offer first and then decline unconditional offer? Do I need to pay deposit as soon as I accept the conditional offer?

Yes you can decline the unconditional off if you’d like to (I did), when you put your firm and insurance choice your other offers are automatically decline so you won’t have to worry about that.
There is no deposit to pay when accepting a conditional offer

Does it work the same way if I applied directly to university instead of from the UCAS? Thank you for ur info.