Personally, I accept that VAT is potentially 'regressive' as defined but certain goods, sometimes deemed necessities, are exempt or lower rated so the impact is mitigated or removed.
Food is one such item. It has been argued that the food exemption gives more cash benefit to the wealthy who spend more on food than the poor but, relatively speaking, the hardship of finding extra cash for food would clearly be higher on the poor than the wealthy.
I suspect the poor are as adept as dodging VAT as the wealthy but probably do so for smaller cash amounts.
By the way, Inheritance Tax may seem to some like a voluntary tax but it is due to raise £4.8bn according to the IFS, not so far short of £5.5bn due from Vehicle Excise Tax. Land Stamp Duty is expected to raise a whopping £12.9bn if it doesn't kill the housing market en route.