I have rented out a (3 bed) flat for the last 20 years. No mortgage, was paid off before we moved and I was able to keep it. At one point, I was going to sell it (to clear the mortgage on the house I was living in, etc) but I am extremely glad I didn't. It's a flat in zone 2, and the rental income has more than doubled since I began letting it. The extra income has given me a lot of freedom around work, and a valuable asset that my son can use in his turn.
There isn't another capital asset that could generate this amount of income, month in, month out, for me. I suspect the same is true for you.
Yes, it can be work and pressure and money, and if you have annual churn of tenants then the agents' fees become tiresome. But if you do it properly, look after the property, don't skimp on things like proper boiler servicing and cover, and warranties on white goods and you buy decent insurance that gives you legal cover and rental income guarantee, then you have a nice, income-generating asset humming along.
Bear in mind that agents want their slice up front (I pay 8% plus VAT, but that is just for marketing the property and finding the tenants. I pay them to draw up the contract, which is pretty standard AST, about £50, I pay for an inventory, about £120, and for credit/right to rent checks on each tenant and their guarantors if they have one. You will need an EPC rating, a gas safety check certificate and an electrical compliance report. Agents should ask for this upfront before marketing your property.
If you are feeling the pinch now, perhaps a good sit-down with your husband and a debt-repayment plan is the way to proceed?