The first path you listed means you'll have no student debt and it will likely be quicker, however most places will insist on you having completed level 3 first, which will take around a year in itself (if you've not completed it already of course!). Level 4 will then take around a year and level 7 will take around 3 - 5 years. However, those who complete uni normally have to complete the level 7 afterwards anyway, although they may get exemptions for some of the exams. This route will mean you'll get no student debt and it could be a good idea to find an employer to support your level 4 so you get in some work experience. You'll be able to stand out from other graduates purely based on this.
However, if you take the route of being supported by work whilst doing the qualification, you'll be working a 9-5 everyday alongside studying in your off-hours, which is quite demanding and tiring. You'll miss out on the student debt wonderfully, but will be more attractive to employers. Doing this route, however, can feel quite isolating (speaking as someone who completed A-levels then went on to an accountancy apprenticeship in a fairly small firm) if you're around the standard age for sixth form as you'll see all of your friends go to sixth form and then exciting places for university. Even if you go to a college in person, people there can be mixed ages and only really speak to people in their own firms as they see each other everyday whereas college isn't that often. However, if you're sure that won't bother you, then working your way up the levels is definitely the way to go in my opinion. I've heard coworkers of my dads who work in a large company in finance even say they regret going to university and wish they'd gone down the other route. I'm happy to help in case you have any other questions you think I could answer?
Good luck for whatever you choose!