Early move out after paying a year upfront

We paid a year upfront for our tenancy but unfortunately a month later we are having to move due to family sickness. We spoke to our landlord who said she would try and find a new tenant and we would be responsible for rent until the new tenant moves in. We said we would be leaving mid March. The landlady has found a new tenant to move in but won’t tell us the move in date for the new tenant, just that she will pay us back our rent monthly starting in July. We believe a tenant is moving in earlier but she is hoping to keep double rent payments for two months. She is requesting that we hand the keys back in in mid March regardless as her partner will be occupying the property until the new tenant moves in.

My questions are -

Can she collect double rent?
Can she require we hand keys back but still be responsible for the rent until the new tenants move in while her partner occupies the property?
With paying a year upfront, this definitely complicates matters as she has confirmed that the money has been spent elsewhere so paying us the money back would need to be monthly as the new rent payments come in.

She’s doing us a favor by allowing us out of the agreement early, and we definitely appreciate that, we just feel like there are a few things amiss here.

If she accepts you keys back and moves in your husband I would think she has accepted a surrender of the lease from that date and you should be due all your rent back from then.

You may need legal advise on this.

As Sally15 says, the day she demands the keys back is when your tenancy ends by mutually agreed surrender. Best to ask her if you can sign a surrender document. She has to refund rent from that point or its a prohibited payment under the Tenant Fees Act.