If you are still unsure after a TIF, then try a TIF at another option, there is no rule saying you then have to stay with that school or give up. The money you spend in the long run will make the money spent on a few trial flights with different schools seem tiny. The overall cost to a CPL is a huge sum of money, and it's your money, get the right foundations in aviation and you can save tens of thousands less than if you get it wrong. The first 20 hours will set you up for the next few thousand, and while you are always learning, getting the basics correct will make the rest much easier.
It's also amazing how many airline pilots make it to thousands of hours with poor techniques or understanding of what they are doing. Sure they are safe enough, but with the right coaching early they could have been much better.