Live in carer through an agency is about £800-1300/ week or more if specialist needs . Live in carer works generally from 8am to 10pm with 2 hour daily break and sleeps over, but you need waking night care staff if the person regularly needs care interventions through the night of 1 carer.
Expect a waking night carer to be in the region of at least £200 per night £1400 per week (10 hours x £20) or more
So potentially you have a £800-1300 week to a £2700 weekly cost there depending in DFs needs and care agency charges
You would cost it up further by working out what else DF needs and what hourly costs for that are - eg for a 2nd carer for transfers of 2.5 hours a day (4 visits daily of 2x45 mins AM and EVE call transfers and 2 x 30 mins lunch and tea time transfers ) is 17.5 hours week x£20 per hour = £350 /week , higher if hourly dom care charge is more . So if £25 per hour then this would be £425 per week and if he needs longer time for 2nd carer visits so could easily be £500/ week
Does DF need someone with him all the time or can he be left at home alone for the live in carers 2 hour daily break? If not there is an additional 14 hours a week x if £20 hour tuis is further £280 for cover for live in carers break
Remember they may charge double on bank holidays etc and there will be other costs such as carer food as well.
But these are carers not qualified nurses and being in a nursing home DF will also have registered nurses caring for him as well, you would need to check what nursing care he has as if you need to pay a private nurse on an hourly rate in addition ...
Another option might be to look at alternative nursing homes - as they do differ.