First thing to say is I’m not a solicitor, I don’t want to say anything misleading, and I stand to be corrected. But for what it is worth I have been through a similar situation, as have several of my neighbours in our housing estate. My house was not finished after 21 months. The contract stated it must be finished in 12 months. My contract didn’t stipulate any penalties or relief.
At the time I was told that – (a) I was entitled to be reimbursed by the builder for the amount of rent I paid after the completion date of my house. (I was paying rent while I was waiting for my house to be finished). (b) I was entitled to look for the builder to complete the house in a timely manner, and my solicitor sent him letters requesting him to finish the job immediately. (c) After unreasonable delay, I could seek the right to finish the house myself.
All of those remedies / reliefs were, of course, based on the specific circumstances I was in at the time and may or may not apply in other instances.
A lot of us were ‘in the same boat’, and quite worried about it. The lesson I learned was that the owner, who was the first to get her house finished, was the first one of us who sought legal advice on the matter.
Good luck.