I'm sorry to hear the business you work for is ceasing to trade and can confirm that assuming you are employed (and not self-employed), this situation would trigger either a TUPE (legislation relating to protecting employment rights when businesses get sold) or a redundancy situation, depending on whether the new owner will be operating a retail premises or not.
I assume the question of whether TUPE applied or not was considered during the sale process. Assuming it doesn't, then you are all redundant.
Redundancy payments are worked out based on your age, length of service and weekly pay. You will also be entitled to statutory notice pay, which will be 12 weeks' pay for your two colleagues and three weeks for yourself.
Contact Acas for free advice or a local HR practitioner or employment lawyer (but be mindful of costs) for more advice.
Ultimately, you all have the right to take this case to an employment tribunal (although fees would apply, which you could get back if you win) if you are not paid the money you are due, and I have every reason to think your case would be successful.
Ruth Cornish is a employment expert and managing director of Amelore Ltd