Re: the bigger picture
This is my fear too. In April you'll have two classes of employee. Those with benefits and rights, and those without. No need to guess which way the bean counters will jump here. An employee package typically adds a minimum of 50% overhead on top of an annual salary (Employer's NI, cost of holiday and sick pay, pension contributions and other benefits to attract employees in the first place).
If the day rate can be kept below this nominal figure then it is madness to employ permanent staff, who also have pesky employment rights.