The actual charges are extremely important here. The fact that an internal organ was punctured would suggest that 'GBH' is more appropriate than 'ABH' in at least one case. The additional circumstances suggest that 'with intent' should be added that 'GBH' charge.
Start by reading about the differences between 'ABH', 'GBH' and 'GBH with intent'. See this document, from the Crown Prosecution Service:
http://www.cps.gov.uk/legal/l_to_o/offences_ag ainst_the_person/
(See paragraphs 45 to 67).
Then take a look at the actual document that the judge must refer to when passing sentence. You should note, however, that the sentences refer to a first-time offender, facing a single charge, convicted after a trial. (Previous offences, especially for violence, can push the sentences higher, as will the multiple offences. An early guilty plea can see sentences cut by up to one third):
http://www.sentencing-guidelines.gov.uk/docs/a ssault-against-the%20person.pdf
(See the table on page 13 for 'GBH with intent'. Page 15 deals with 'GBH', while page 17 has sentences for 'ABH').
Additionally though, it's possible (indeed, probably quite likely) that the judge could pass an 'IPP' (="Indeterminate Public Protection") sentence. That's effectively the same as a life sentence, in that the judge sets a 'tariff' period, before which the offender can't be released - but his eventual release can't occur until it's deemed that he no longer presents a risk to society.
My guess (based upon some fairly limited information), is an IPP, with a tariff in the region of 5 to 7 years.
Chris