I advise contacting this user via the thread instead of PM and using a well known escrow. I am not familiar with ukash, but I also assume it is reversible, so I wouldn't trade him bitcoin for it.
Why? Who are you?!
Your first few posts were about buying bitcoin via PayPal, an extremely easy to reverse payment method. I don't know about ukash, but I assume it's also reversible, in which case escrow won't do anything.
Trying to buy bitcoins as a newbie is going to be challenging for you unless you're paying upfront or through escrow with an irreversible payment method.