Re: "the cost of which would be automatically taken from their wages"
"IIRC the working time directive states that your employer must allow you to take a minimum of half an hour out of the first six hours, and fifteen minutes out of every subsequent three hours. Which is all good for your health. It also states that you MUST take those breaks."
Alas, no, you do not recall correctly. As a union representative, I find this to be possibly the most frequently misunderstood area of employment law and you may well be surprised at the actual law - most employers are more generous than the law demands, but you don't have much in the way of legal entitlement to working breaks.
the following extract is from the EU Working Time Directive page on UK.GOV
"Workers have the right to one uninterrupted 20 minute rest break during their working day, if they work more than 6 hours a day. This could be a tea or lunch break. The break doesn’t have to be paid - it depends on their employment contract."
And that's it. No other entitlements to breaks or rests etc. There is a clause in H&S laws however about extended VDU use (love that old fashioned term) wherein you are supposed to spend 15 minutes away from the screen every few hours; not a break, however, just different work.
There's lots of advice to employers about letting your employees take breaks to maintain peak productivity, but there's no law making them do so.
As an aside, the most frequently ignored or unknown rule I come across is the minimum break between shifts. I all too often meet with employees who are finishing late and starting early, especially on shift patterned work.
Again, from the Working Directive:
"Workers have the right to 11 hours rest between working days, eg if they finish work at 8pm, they shouldn’t start work again until 7am the next day."