The most important bits are not part of the service history.
In terms of priority, I think you should check whether the car has changed the timing chain and how many times this has been done. If the DPF light is on, the chain will have stretched and will need replacement. If you have forscan, ask whether you can read the chain angle.
Check when the chain was last changed and compare with the current mileage. There is a good chance that you will need to replace it soon. Every additional chain, needs an earlier replacement than before. It is a big cost even if you DIY which is not really easy. You can buy these cars at auctions for about £500 plus fees and a chain replament will cost you double that.
Check whether the injector seals have been replaced and do the same for the turbo.
In my opinion, if you find out a chain, injector seals, turbo replaced, you are looking in a well used engine which sooner or later will require one of the same again.
Check that the car has DPF and EGR in good working condition. If you find any service history, check whether they ever used C1 oil. Go through the trip computer and note the figures for average speed and consumption. If the speed is below 25mph, it means a really hard life for the DPF as it needs to be driving more than 25mph to regenerate. Usually it will go together with a low mpg figure as well.
Check that the rear callipers are free. You should not hear any noises when you release the handbrake and try to move. Drive a very short distance without using the brakes. Get out and attempt to touch the rear discs. Do not go on the full attack, but just a gentle touch to get a feeling how hot they are. Compare with the fronts. If the rear callipers are not free, the discs will be warm instead of metal cold.
Other than that the service intervals is just oil changes. Every 5th service it says about gear oil as well and every 6th service it says about replacing the injector set up which cost about £1K at the dealer. You replace the air and cabin filter every 2-3 services but this is just a 5 minute job, but at the same intervals you replace the fuel filter. Every second service you need brake fluid.
With a 10 years old car, it all depends on how much you will pay for it considering how much work it needs to keep rolling. When you compare the cost of service vs repairs, getting service history is not that important as the repairs will cost multiple times what you will pay for the car.