Hello and welcome. It wouldn't be peer to peer trading, but coinbase is also simple to use. I am not sure how quickly they give you the btc you purchase however.
Coinbase is easy to use. However, your first purchase is limited to 10 btc and you don't get them until 4 business days after your purchase.
Once you have reached "Level 2" you get your btc instantly; however, you can't get to Level 2 until you have bought your first btc and sat on your hump for 30 days