Make it clear to the realtor(s) and your lawyer that the offer was submitted based on the information provided in the listing re year round home. You do have a responsibility to the seller as you have a contract and may be liable for his additional expenses ... if any. However the law is also very clear re the responsibilities of the agent(s). If you have legal problems as a result of agent misrepresentation you should be able to 'lay them at the door' of the offending agent. BTW the agent is actually the firm who employs the sales rep who sold you the property, that would be the broker of ABC Realty who employs the salesperson. If you no longer trust the 'rep' talk to his broker ...who is the actual 'agent'. Don't deal with the rep anymore. Keep copies of all your paperwork including the listing, make notes of what you were told, when and by who. If you encounter problems there shouldn't be penalties that won't be covered by the agents. If you incur significant costs resulting from agent misrepresentation talk to his/her broker and give them the opportunity to 'reimburse you in full before you file a complaint'. They'll probably bend over backwards. Try not to worry too much, it should resolve itself quickly.
Just to cover all the bases, make sure that the lawyer is right! lawyers (like agents) are not perfect! It would be a shame to lose the property because the lawyer erred. I suggest you take your copy of the offer into the planning department at the municipality. A clerk there can pull the file and explain the limitations of permanent occupancy on the property, or reassure you that there won't be a problem. Don't even remotely consider suggestions that you close and try to bluff your way into full time occupancy if it's not 'legal use'.
'Broad brush' comments regarding the character, motivation and integrity of real estate agents demonstrate ignorance on the part of the contributor(s).
There are 45000 agents and brokers in Ontario who are required to fulfill ongoing training to remain lisenced. Almost all of them are competant. Any agent who does sloppy work for a cheque won't be in the business for long. If you hire an agent, ask friends or family for a referral ... and respect their time. Avoid phone calls before 8:00 a.m. or after 10:00 p.m. unless urgent. Remeber, they might like to get out fishing once in a while too.
I earn what I'm paid by working long hours evenings weekends and holidays (including Christmas and Easter). I'm just a guy with four kids who don't turn out the lights like the rest of you. I don't go around looking for a soapbox but sometimes enough is enough....and I don't fish muskie