just wondered, do you always need to deposit a certain amount of money to play online or are there any pay as you play sites, or any free play games to practise on?
Not always - there are a number of free sites out there, and some of the pay sites will let you have a look around before you have to give them money. You can look for sites that offer free cards first as well.
The only problem is if you use the free cards on a site and win make sure that you check the fine print. Because a lot of places will not let you get your winnings unless you have deposited a certain amount.