Let's leave the 'with intent' bit to one side for the moment.
The relevant charge for an assault is determined by the level of the injuries sustained by the victim. An assault resulting in the need for stitches normally counts as 'actual bodily harm'. It only moves up to 'wounding' if there is permanent visible disfigurement which is of more than of a minor nature. So the assault MIGHT come into the category of 'wounding' but, without access to a doctor's report (and a legal opinion on that report) it's impossible to be sure.
If the charge is 'ABH' then a court would have to examine whether your injuries come into the 'serious' category within the ABH bracket. I suspect that the judge would decide that they did, so that puts the 'harm' factor to 'high'. The judge would also have to determine 'culpability'. Given the sustained nature of the attack, I suspect that culpability would also be rated as 'high'. Those two factors together would mean that (if your partner pleaded 'not guilty' but was convicted after a trial) the judge would normally have to pass a sentence of between 1 and 3 years imprisonment. (If your partner pleaded guilty at the earliest opportunity the range would drop down to 8 months to 2 years).
If the charge was 'wounding' (but without 'with intent' added to it), the judge would again have to asses 'harm' and 'culpability'. It's likely that 'harm' would be assessed as 'low' (within the range of wounding offences) but culpability would still be high. If so, the sentences would be the same as in the previous paragraph.
'With intent' can only be added to a 'wounding' (or 'GBH') charge. (i.e. there's no such thing as 'ABH with intent'). A repeated attack, the deliberate selection of a weapon or the use of a weapon against the victim's head all constitute reasons for adding 'with intent' to a 'wounding' charge, so it seems quite likely that 'with intent' will be added if your partner is charged with 'wounding'. Sticking with the assumption that 'harm' is assessed as 'low' but 'culpability' is 'high, that would mean a sentencing range of 5 to 9 years after a trial or 3 years 4 months to 6 years with an early guilty plea.
The actual time spent 'inside' is usually half of the nominal sentence.
References:
http://www.cps.gov.uk...es_against_the_person
See paragraph 46 for the definition of 'ABH', paragraph 55 for the definition of 'wounding/GBH' and paragraph 65 for the factors adding 'with intent.
http://sentencingcoun...ine_-_Crown_Court.pdf
Chris