As another comment said, and I can confirm from personal experience, just the fact that you need these to enforce a non-compete is no panacea. There is usually enough probable cause, or whatever legalese name it has, to take an employee to court and cause them enormous havoc and expense (UK anyway, but the rest of your post reads consistent with UK laws).

Additionally, if you think you are small fry for a firm to sue you, not necessarily. Enforcement of non-competes is just as much aimed at deterring others from trying as it is at affecting you personally, if you spread the cost for the company over the 10-20 employees who are deterred, it suddenly looks cheap.

Even if against the odds of going against a large corporation with deep pockets you eke out a win in court, you are almost certainly not getting all your money back, and none of your time and stress either.