I have a petrol XE (MY20) and have had just one service so far (Jaguar specify only every 2 yrs of 21,000 miles). This was around £450 at a Jaguar dealer, so not cheap. Jaguar independent specialists will probably do it for around £200 -£250. I think the 2yr/21k miles interval is too long so I do an intermediate engine oil and filter change myself. This is easy - the oil filter is at the top of the engine, and the oil can be sucked out of the sump via the dipstick tube using a PELA extractor, so no need to get under the car at all!
As for diesels, it does seem that quite a few people have had trouble with DPFs not regenerating properly if the car is used for mainly short journeys - which might be the case with your 7000 miles/year. This causes the ECU to actuate a forced regeneration which squirts excess diesel into the engine to get the DPF hot quickly. Trouble is, some of this excess diesel can find its way into the engine oil thus diluting it and causing it to lose some of its lubricating properties. Earlier XEs and XFs with the diesel engine have also had problems with the timing chains & guides - which are located at the back of the engine, so need transmission, torque converter and flywheel removal to get at them.
All in all, with your expected low mileage I would recommend you consider a petrol XE. I get up to 40mpg on long runs, 32-35 on shorter runs and, at 7000 miles per year, I don't think you'll save a lot of money with the diesel's admittedly better fuel consumption.
My two-pennyworth anyway...