Incorrect Advice/tax relief

Hi, We received incorrect advice from an accountant regarding tax return. We rented our only property out and moved in my parents due to issues with neighbours. It was an 8 month rental with the property straight on the market as we knew it was always to be sold for our new home as did the tenants as they only needed a few months till their home was built also, with a residential mortgage as it was never for business, purely until it could be sold and we could purchase our new home. I took advice from a local accountant at an appointment and they advised me as the income was low we did not need to contact HMRC as we are under the threshold. I have however now received a letter from HMRC advising they see we had a rental property and we need to inform them. I am concerned of penalties as we took advice but I have nothing in writing etc about this as at the meeting they said there was nothing to be done and that was that. The company has also shut down and I have found out they have been giving bad advice to local companies. Where do I stand with this? I also am unsure regarding the £1000 relief me and my partner can claim on the rent. Can I also include with that the money paid to advertise the property, to sell, the cleaning costs, boiler services and maintenance? Or just some of them? The information is not clear. In regards to capital gains I do not think we require this as we are covered by 9 month grace period I believe even though we did not live in the property? I have tried talking to HMRC agents as our situation is unusual but I am not finishing any clear answers and I am concerned about filling out the notification form. Apologies for the long query but I am very concerned this accountant has given us incorrect advise and we are liable Thank you

Hi,
Thank you for your question, with regards to the ongoing issues with your accountants and bad advice I am afraid that you are still responsible for the agents mistakes, if you have not already completed your returns I would advise you complete them as soon as possible to address any potential penatlies and ongoing interest.
Once the balance is established we can then look into the appeal process and see what can be done:
Check if you need to send a Self Assessment tax return
Appeal a Self Assessment penalty for late filing or late payment  
Self Assessment: UK property (SA105) 
Should you need any further help please contact the helpline.
Thank you.