The number of tennis camps and community tennis courts with pros is substantial in this country so you can spend almost nothing or the second mortgage on your house. Confidence on the court is very important. The learning experience is the same for players of all skills and experience levels. It generally takes about 2 months of hard, daily practice for a professional player to make a major stroke change and to be able to execute it under pressure. A club player, like us, should adjust expectations accordingly.
Nothing happens in tennis or anywhere in sports, overnight.
Now that you've learned a new stroke from the pro, you need to be able to take it onto the court with others. One way of doing this is try to make your practices feel like matches as much as you can. Eventually, your practices should have an intensity that rivals your matches so that the transference of skills becomes natural. As your confidence grows, you should see an increase in your ability to use that new shot, grip, serve, etc. You'll know it has become a part of your game when you no longer have to think about it.