Vicious landlord

Hi all, I am opening this discussion to get informations about my legal rights.

We are a family with 3y old girl, renting a split level flat from the landlord for 17 years, never late with payment, never had a party or noisy visitors, house was always well maintained and clean. 

8 months ago, as our landlord was a bit short with money, we decided to rip off the 20y old carpets and put nice laminate floors. As I am an interior designer by trade, I renovated the old wooden stairs, choose a nice, neutral in colors, and expensive paints, and as I like everything to be done perfect, I painted the walls myself. I designed gorgeous curtains and sew them on my own sawing machine, well, basically I gave this flat a very posh touch. Living in it, I everyday spend couple of hours to design and do something, like an artist painting a perfect picture, for 8 months.

Normally I would charge for so intense work nearly 20'000, but this time I thought, that (after 17 years living here) I am doing it for myself, assuming, that my family will live here another 20 years or so., and didn't charge the landlord a penny for either materials, expenses or my creative work

Two days ago we have got an information from the landlord, that she decided to sell the house and we have to move.

I don't like to make any troubles to anyone, and I don't want end up in court claiming my rights, but I am feeling cheated on and very disappointed. 

Does anyone here knows what are my legal rights?

Thanks, Eliza