PCPs are usually set to work bet with a minimal deposit. Historically they were set up to give enough equity over the GFV (final payment) to roughly give the same deposit if the car is part exchanged on the next car. This is why they exist.
There are two other options; 1) hand back, which should only be exercised if you have negative equity at the end, in this case you would then "lose" your deposit, but effectively the finance company are clearing your negative equity. 2) Pay the GFV and own the car.
As car companies want you to use PCP they usually have a lower rate. If you want to own the car ultimately, to get the best deal use the PCP then set up either a saving plan to clear the GFV in 3 or 4 year or whatever period your PCP is over. Or simply finance the GFV with a low rate personal loan.
The down side of an HP is that if the car depreciates more than usual you have no protection other than your rights under consumer finance law.