For the sake of the OP, I didn't go into who raises the fine and who issues it, when absence can be authorised or not etc. As I originally said, I would expect a fine but not a prosecution, and the best thing is to speak to the Head in advance.
There will be cases when holidays don't result in fines, or do result in prosecutions, and cases where the Head's discretion has been applied, with the support of the governing body.
I doubt they need to know all the ins and outs, but it is public information and can be found here DfE Working together to improve school attendance
Penalty notices must be issued in line with the Education Regulations 2007, as amended and can only be issued by a headteacher or
someone authorised by them (a deputy or assistant head), a local authority officer or the
police.
When a school becomes aware that the threshold has been met, they are expected
to make the following considerations to decide whether to issue a penalty notice in each
individual case:
• Is support appropriate in this case?
If no, for example a holiday in term time, a penalty notice should be issued
subject to the other conditions below.
• Is a penalty notice the best available tool to improve attendance and change
parental behaviour for this particular family or would further support or one of the
other legal interventions be more appropriate?
• Is issuing a penalty notice in this case appropriate after considering any obligations
under the Equality Act 2010 such as where a pupil has a disability?
If the answer to these questions is yes, then a penalty notice should be issued. If
not, another tool or legal intervention should be used to improve attendance.