Nominally, Common Law, the system of law that to a first approximation is used in countries descended from the UK, has a lot of protections of that sort. You can't put "unconscionable" terms in a contract, e.g., it is simply illegal to sell yourself into total slavery in common-law derived systems. All signatories to a contract must consent, must not be under duress, the contract can not be one-sided (this doesn't mean "the contract is 'fair' from a 3rd-party point of view" but "the contract can't result in only one side giving things but the other doesn't"), and a variety of other common sense rules.

In practice, availing yourself of any of these protections is a massively uphill battle. Judges tend to presume that these common law matters are already embedded into the de facto legal system because the people writing the laws already operated under those assumptions while framing the law. Personally, I disagree and think a lot of these protections have eroded away into either nothing, or so little that it might as well be nothing, but you have a 0% chance of drawing me as a judge in your case so that won't help you much if you try.