Picking up on what @EdithDickie said about the 25% deduction, where the client is a minor, the damages have to be approved at an Infant Approval Hearing, which is a short (10-15 min) hearing where a Judge makes sure the child is being adequately compensated for their injuries. At that hearing, you have to ask the Judge for permission to deduct the 25% from the damages. Some Judges agree, some don't, so it's not guaranteed.
The money will either go into the Court Funds account until the child is 18 or, if the Litigation Friend comes across as trustworthy and shows that the child has an account of their own with a better interest rate, they will release the money to the LF for investment instead.
I work in public liability claims, and this case falls under the Occupiers' Liability Act '57 (the Act which deals with lawful visitors, there's another Act for trespassers). I'd want their risk assessments / inspection records / maintenance records, plus any specific documents about that pipe. From those you'd decide if there was negligence on the school's part.
From what you've said, I'd definitely go to a PI lawyer and get those investigations done as it sounds like a nasty injury which will scar, and that's exactly the kind of injury which should be compensated.
You can also PM me with any questions.