Your boss seems to have approached a company in order to keep everyone employed on some basis. He either has to sell the company as it is - a going concern, insolvent but still trading and the new guys take on the staff and all the debts etc. In that case you are part of TUPE which means that your 10 years will count towards any redundancy and (I think) that they have to keep all salaries the same. Or your boss has to put the company into Administration. It may be that the Administrator will keep it trading and try to sell it as a going concern or it will go into liquidation. The liquidator can then sell the 'goodwill' (ie the client list and will also have to sell all the assets to pay the debts (which will actually mean that he will sell all the assets to pay his fee!) You will get redundancy (from the Government which won't be massive but will be something (Google it and you will find out - BusinesslInk website will have info) and you will be able to set up as a freelancer.
A freelancer cannot work exclusively for one company. They are deemed to be employees. Many companies try and take on freelancers that way to get round having to pay Emloyers NI, but it will be spotted.
If your boss has not sold the company and is not able to trade then he has to go to a business recovery firm (who may well tell him it's too late) or an Insolvency Practitioner and quickly.
Do NOT resign. The 'new guys' have not bought the company and have no legal rights. They cannot ask you to resign. If your boss goes for liquidation then you will get any pay owning, redundancy pay, you will be able to sign on, you will get any holiday pay owed to you. If you resign from a job (I think I'm right in saying) that you cannot get unemployment benefit/job seekers immediately.
Good luck with it. I'm sorry that I hadn't spotted all the posts or I would have put my twopennyworth in earlier.
I have been through a couple of company liquidations and they are not good for anyone concerned.