No, not at all, cath. It doesn't just apply to healthcare workers - anyone whose employer is registered for this scheme with HMRC can apply for tax relief on purchases of clothing to do with their job.
In the NHS uniforms are provided, but not tights or shoes - in for instance freight hauliers, if there is a uniform of trousers and tops, the men still have to buy their own toetector boots and can claim relief on the purchase as long as it's only for work use. OH has done it in the past, he only can't do it at the moment because his company hasn't declared to HRMC that they don't provide uniform boots for their employees.