If you have rental income you have to pay income tax on it. The tax can be offset against any form of maitenance or repair on that property. If you put new windows in for example valed at �2500 you would not have to pay �2500 of tax accrued on that property. This offset against tax is deferred to future years. If you are going to rent out a property and do not want to pay tax on it keep doingthe house up new boiler, drive, fence, etc. If you had a mortgage you would be able to claim the tax back against the intrest on it.
Not sure if you can do the following but maybe worthwhile seeing if you could get your tennats to pay the rent / part rent for the property you would be renting together. If you can do this you would not be getting the income your landlord would. I would suggest that you pay a small fee to a tax / financial adviser who shold be able to give you the best advice, this is tax deductable. Can you let me know what they advise.