This would fall under criminal legal aid prison law.
Not all criminal legal aid firms have a prison law legal aid contract and those who do are limited to parole board and tariff type cases and adjudication.Legal aid is no longer available for the large majority of prison matters as is used to be.
As the issue is parole board related then legal aid should be available.
You would need to find a firm with a prison law contract.
The link here will help you find a legal aid firm.
The following link will allow you to look for a legal aid law firm.
Enter a local post code, select the area of law, ie family, crime etc and a list of local firms will be displayed, then all you do is simply call one.
Also it may be easier to find a legal aid prison form if you check out the inside times paper, many prison law firms advertise here.