Hi there, thanks for your patience. Whilst the specific terms of the contract may not be applicable until the job starts, there would still be a contract in place due to the employer having offered you a job and you subsequently accepting it. There would therefore be a contractual understanding that you had agreed to take on the job in question so if you were to fail to go ahead with your promise, you could be acting in breach of contract.
Whilst they cannot force you to work for them, it is possible for the employer to consider suing you for breach of contract for any losses incurred as a result of your breach. However, they have a duty to try and minimise their losses so initially they must start looking for a replacement straight away. If they find someone to take your place in time then the likelihood of them suffering any of the losses they are trying to claim for is relatively low so it is unlikely they will go any further with this. Also they must be able to show that they have actually tried to get someone in your place, they cannot just sit back and do nothing.
So in summary it is possible for them to consider a breach of contract action but as mentioned they must be able to show that they have suffered actual losses as a result, which were unavoidable and that they had taken steps to try and mitigate these.
This is your basic legal position. I have more detailed advice for you in terms of the rights you have should they actually make a claim against you, which I wish to discuss so please take a second to leave a positive rating for the service so far (by selecting 3, 4 or 5 stars) and I can continue with that and answer any further questions you may have. Don’t worry, there is no extra cost and leaving a rating will not close the question and we can continue this discussion. Thank you