I don't think your chances would be decreased massively by picking Philosophy, Politics and Economics but I do think unis like to see a student with breadth.
Choosing those A levels could certainly show your interest in the degree though, however (in terms of Oxford PPE) they don't stipulate that you have to study any of those as a requirement. They do say that Maths is recommended, but I've seen data somewhere that shows a small number of those without are offered a place though you will have to have an aptitude at Maths, could be shown through AS level but they're less common these days. "Of the 192 applicants offering A-Levels who were awarded a place, 171 (89%) had Maths."
It also says History is helpful- History links well with all those subjects, if there's one you're not as keen on, and you're interested, then that could be a good choice.
Similar degrees to PPE are mainly single or a combination of those subjects, e.g. Economics and Politics, Philosophy and Politics.
The civil service doesn't seem to have preferred degrees, I think they like to have a range of people and their experiences but you'll need skills relevant to the job. There's graduate schemes and even apprenticeships alternative to university. I'd suggest researching if you're interested.
I don't have experience with those A levels as I'm going to sixth form this September but we have similar interests and I chose Politics. I think at the end of the day you need to pick A levels you're interested in and think you'll do well in because grades are important to universities but still make them relate to degrees you may want to pursue.
https://www.ppe.ox.ac.uk/admissions-statistics ^From Oxford about PPE admissions and the statistics, it could be helpful to look at previous years and those who were accepted.