AFAIK UK companies have to deposit their annual reports with Companies House, where anyone can see them for a small fee. Most of the FTSE ones publish them on the web.
Anyway, her argument isn't with FTSE businesses, it's with foreign-owned multinationals who have the ability to move profits around the world and reduce Corporation Tax payable in the UK (although they still have to pay VAT, rates, employer's NI etc etc). But it's a fundamental principal of the global tax system that profits should be taxed in the country where they're generated. And it's difficult to argue that the bulk of (say) Apple's or Uber's profits are generated anywhere other than California.
It's also often conveniently forgotten that businesses are taxed on profits, not revenue - Amazon (last time I checked) have never made a global profit, preferring to invest any surplus in their business. So the fact that Megacorp had a billion pounds in revenue in the UK and only paid a million in CT does not imply a tax rate of 0.1%. Margaret Hodge understands this perfectly well, as her own family business - Stemcor, a global steel erector - paid very little UK tax on its worldwide revenues of c $10 billion, for the simple reason that they made a loss.