Good advice from hazell42 and others. Moving house, especially being forced to, is horrible and very unsettling.
However, try not to panic. Houses don't sell instantly and it may be worth speaking to your landlord about the possibility of selling with you in place if you have a good payment record and it is the type of property that would appeal to investors. If not, then he/she may want to keep their options open - which doesn't exactly help you, but may give you more time to think and to look at your options.
My guess is that your landlord will want to keep you on side, and it may well be that he/she will be able to be flexible. Speaking as a landlord, the last thing I would want would be a disgruntled tenant in the property when I am trying to sell it!
Obviously, I have no idea of how well you get on with your landlord, or whether they are a professional landlord or just renting out their own home, but it may be worth asking them if they know anyone looking for a reliable tenant. Do be careful though and don't agree to give up occupation until you're definitely sorted - or LL has that possession order.
Horrible to lose that sense of "security" but there are options and your landlord will have to give you notice and go through the statutory procedures, which gives you some breathing space at least.