Jan,
You donāt say if the 2 bed is above the three bed, or if they have seperate entrances?.
But you do state part access to a garden but is all yours and is it split between with both properties.
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Apologies for not asking if there was any date like itās the local council planning to build a carpark or anything they have to tell you about like selling it at forced sale value?
Jan, Thereās lots of people here that will guide you in the right direction.
I donāt know the layout, and without spending money by doing construction work? Taking what has already been said about 3 bed flats v houses. Is it at all possible to create a studio apartment? So you would have 2 X 2 bed plus a studio one bed in lounge with bathroom/kitchen facilities. Perhaps a 3 bed flat could be split into two large one bedroom units, or two small two bed units, or possibly simpler to alter the 3 bed (dry.wall?) To a 2 bed plus studio.
I guess it depends on position as much as anything, I think the view of a fried chicken store wonāt beat the views that youād find in rural areas. I do know that most people are looking for somewhere secure that they can afford and feel safe in. I think the figure that you gave quite low. Is it a built up area?
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āWife Contacts letting agency after seeing ideal properties in Ashingtonā.
āIāll have the downstairs flat, and as for my husband, well he can live upstairs with the storageā
Jan if I was married, I could be tempted by that arrangement 
Have you considered waiting until the 2 bed is empty and changing it into two houses? I know itās an outgoing, but value-wise with a garden access. Wouldnāt that increase the rental value? .
One staircase required, but the difference in rent from 2 flats to 2 houses, there I think youāll notice a large enough difference?..
Although if your 3 bed flat is on the ground floor, and you made sure it had garden access you may be surprised by the amount of disabled people who would appreciate a ground floor flat. Even if it means you keeping your eyes open to see if thereās a pathway or plot that would help you expand the garden because it isnāt expensive but it could help you offer the all important garden. During to he watmer months a garden becomes an outside room and Jan if you donāt have a garden especially in summer it would lower interest, a family I think is unlikely as a tenant without one
I think if you did the little bit of research that someone suggested is a must, & think you must be extremely busy to purchase a property and have an empty 3 bed flat after 6 months? did you ever advertise it?. I know you said you hadnāt had much luck.
Is there s floorplan? Even a basic sketch would give us more ideas, photos or anything your surveyor had drawn up would be helpful too.
Jan, there is always a solution, and Iām sure that all will become clear.
Relax 
and donāt let it worry you, not knowing about the area is not going to help me suggest the best you could do.
If the area is quiet, and you could fit a chair lift for the upstairs flat, petjsps alter the bathrooms to wet rooms and then you would be in s good position to rent to those who have s disability, a carer & any equipment? You can advertise here and maybe take a look at the disability housing register for further information?.
Or you could just advertise your vacancy and see what response you get?
All the best, kind regards Lynda 
It had some viewings + I had some potential tenants but it always felt through. Flat is in good/ok condition .