If you owned the house outright I think the best thing to do is renovate it and rent it out. There is no need to pay an agent a monthly fee. We paid an agent an upfront finders fee for the tenant and then just managed the property ourselves, it’s very straightforward.
As it’s shared with family perhaps they want/need the money. Your mum might want to enjoy a few luxuries. What you should do as a minimum is understand what the property is really worth, agents are desperate for business and if they can get a quick sale (at a low price) they will favour that over a higher price that may take many months.
As for all the doom and gloom about property not going up the fact is over the last 50 years property has been an outstanding investment, today there is very little you can earn a return of 5% on without taking a lot of risk. Indeed you will be subject to CGT on a sale but your allowance is 10k a year, so if you own 40% of the house it can go up 25% a year in value in a year before you hit that.
EDIT: in response to bamboo if the property is empty you can probably get a council tax holiday, our local authority allows 6 months with property empty and you pay no council tax. Given your uncles death you should do that immediately anyway.