You can get an independent valuation for the property value, I assume a solicitor should be able to advise about agreeing the value of contents - won't your brother have this own furniture he'll won't to use? In which case you could sell any remaining furniture
You will need to get a value on death for probate anyway. I got a chartered surveyor to provide this (for a fee) as the Probate Office would accept this without quibble. Alternatively, you might get 3 estate agents to provide valuations - though they will then keep contacting you in the hope that they will be appointed to sell the house for you. Contents are rarely worth much in practice unless your DF had recently invested in expensive furniture etc that your DB wants to keep.
I think with contents, try to be pragmatic and try to be fair. Fair doesn't have to mean an absolute even split, if the furniture would be practical and is custom made to fit a space in the home, maybe your brother should keep it.
It depends if you want to have a sit down and pick particular things you have an affinitywith or holds sentimental value, then which would actually be practical to you.
It's best to get the house valued by at least 3 agents and get an average from those valuations.
Sorry to hear about your dad's ill health, I can understand how difficult a time this must be