Say I am selling my home to a buyer and also purchasing a house from someone, and the chain of sales goes no further than this (for the sake of simplicity). All house sales are in the UK, where you agree on a date of completion (date of move) and exchange contracts prior to completion to make this legally binding. If anyone pulls out of the process after exchange of contracts, then there is a contract breach, and this can be particularly problematic for a buyer pulling out. An answer here suggests some of the potential knock-on effects of not completing a property transaction after exchange of contract.
At the current moment in time, the UK government has guidelines that instruct people to isolate for 10 days upon suspicion of COVID-19 symptoms or a positive COVID-19 test. From the government, it suggests you risk a £1000 fine for breaching self-isolation (as far as I can gather from the website. I'm unsure if there are further penalties).
Let's say we get to 5 days before the transaction completion date stated in the contracts, and the person at the top of the chain (the person I am buying from) makes me aware that they have got a positive test for COVID-19 and have to self-isolate for the 10 day period. This would overlap with the completion date set out in the contract and mean that they can no longer complete on that date if they are to follow government guidelines.
Now, I presume that all parties can mutually agree to either ignore the date (complete but remain put where they are) or rescind the contracts and set a new completion date. However, can someone in the chain refuse to do this and force through the completion date despite the COVID-19 guidelines? As an example, could the people purchasing my property just say they don't really care about my purchasing transaction and still want the completion date honoured? Would I have good legal standing to refuse them based on the circumstances, or would I still be liable to a lawsuit if I refuse the transaction?