I have been looking into loans as the apr is a lot lower than any deal on many cars new or used around right now. Santander 2.8% and post office i think the same, if you have good credit rating should be no issue. Considering the allowance now over the 3 years of the mb lease is now just over 10k. Are a few cars around with 0% apr but all are manuals. Kia do do the 7 year warranty and you can buy a 3 or 5 year service plan. 5 year is £699. for me that’s affordable on a smaller car maybe a rio and in the end you will own something.
There are some 0% deals from other manufacturers as well, not just Kia (see link below) and there are still some big discounts to be had. Brokers such as Drive the Deal are useful as they are brand new factory orders from main dealers at big discounts. I’ve never bought through them but have used their prices as a tool to get local dealers to match, or come very close to them.