So is the difference in P2P, you don't put a buy order and wait, you buy or sell crypto directly to one another?
If you want to purchase bitcoin instantly without waiting then you can go for "Coinbase". By using your debit card you can buy bitcoin from there. As a beginner its better to follow hastle free way to get your bitcoin and after getting your bitcoin you can use " Coinbase" as a safe wallet.
Although coinbase bitcoin purchase fee through debit card is slightly higher (3.95%) but quite faster and safer.