If they take her to Court she will get a form to complete showing her income & expenditure, & the amount she is offering; it also shows details of other debts & what she is paying them. If she is paying them a lot more on a pro-rata basis then it is likely her £5 offer will be rejected. She should really work out the total amount she owes to all her creditors, the total amount she can afford to pay each month & pay each of them a pro-rata amount.
Also, she will end up paying the Court fee & other costs - which will increase the debt considerably - & have a County Court Judgement on her credit record, which will mess up her credit rating for 6 years even if she does pay the debt off.
If she can possibly manage it, much better to offer something they can accept.