Ive only signed a couple of contacts ever, where the company really wanted it and were not forgetting.

I may be wrong but the offer letter is enough to insist your first paycheck and from there on in its obvious the company thinks you are an employee therefor subject to all employment law, most of which is about not changing the staus quo without due process. E.g. In the EU holiday pay cannot be lower than the previous 13 wk average doesnt matter what your contract says.

Employment law as far as i have seen in the UK (thanks to the EU) is all you are ever going to get anyway in any tight situation. Anything else in a contract is likely only gling to be an attempt to reduce that liability (which then in turn often invalidates the whole thing anyways).