Have you gone onto the tax credits site and tried their calculator? (I don't know if they still have it, thought there was some rumour of it being removed from the site) but that should have everything on there to show you what you may be entitled to. Tax Credits rules have changed slightly, and are due to change again in May (though it's difficult to say how). Currently if you are a couple, you need to be working 26 hours a week (I think, please check site) to qualify for tax credits. There are other factors as well - you said something about job always having accidents, is this something to do with an injury claim? If so I think there may be other support you can get but you'd need to get some advice for that. If you have a citizen's advice bureau still active in your area (I know everyone tends to glibly say 'Go see CAB' without realise CAB has had a lot of funding cut), but it would be the first place to go, as they may be able to help you with PIP/DLA claims if you don't have them already, and other things you can do for assistance and support.
*sigh* yes, fun and games. The coalition has really done a number on the social services system. Again, I'd try and get in touch with CAB if you can and see if they can point you in any direction.
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