I would think the 7 of you would need to come together and discuss your options, perhaps with a mediator. It will take the agreement of all 7 of you to sell, so perhaps you could determine how many want to sell.
And clearly your brother is refusing to give that permission as he has no place to live if it is sold. So does he want to rent it off the other 6 of you?
As joint owners you will need to organise insurance, maintenance, tax on any rent, etc etc. maybe you could exchange all of these costs and allow your brother to live there rent free?
If he refused to agree to sell the house ownership will have to transfer into all your names, & make sure as an owner you have access to your property etc.
Alternatively if I was you and had a sibling with a bit of money offer to sell your share at a knock down price to them, take the money and walk away from the mess.
Otherwise all you can do is go to the high court, get your brother removed as co-executor for failing to carry out the wishes of the will. Then go to court to get him evicted. Then actually enact the eviction. Sell the house, pay all the legal fees, and probably end up paying more legal fees out of your own pocket.
Your solicitor will probably give you a good realistic estimate of fighting your brother all the way through the courts and how long it will take.