I'd just like to dispel the myth that good grades at school results in good jobs. The whole point of compulsory school education is (or at least should be) twofold; to teach children basic skills that will help them out in later life, and to seperate children into academic skills levels using exams. Not getting high enough grades does not mean you have ruined your life - it just means that you are perhaps not the more academic type.
Academic jobs are not necessarily the highest-paying (as with the good example Vlynor gave), and the highest-paying jobs are not necessarily the best - that is highly subjective. Some jobs pay a lot because either their conditions are undesirable otherwise (e.g. dangerous working environment), or require undesirable specialist training or education beforehand (e.g. long university courses like medicine or law). In most countries with uncorrupt employment systems, you roughly get paid what you sacrifice.
I have unfortunately been fed the bullsh*t of 'good grades = good (high-paying) job' for most of my life by my parents. It is only recently towards the end of a medical degree that I have been struggling and suffering through, and after seeing the highly-stressful work environment of a hospital doctor that I realised the higher pay is compensation rather than a good deal. Someone working a minimum-wage job is getting an equally good deal as they won't have to endure as much crap.
My advice would be to firstly consider what type of employment you enjoy - I'm not sure if you actually enjoy manual work, or are just feeling you have no other options. Even if you didn't do so well in your exams, I am sure there are plenty of other opportunities to pursue more academic work.
Then, secondly, my advice would be to consider how much you personally value money. How much are you willing to sacrifice in terms of time, effort, discomfort, safety, etc... for that larger pay-cheque.
Hopefully that should give you a rough idea of the type of job that's right for you, without any of the ignorant and over-simplified miscinceptions about good vs. bad jobs.
Hope that helps bro.