If you had a "normal" work permit, you'd be eligible to continue working on that permit - even after it expired - if you applied for PR via the inland application process AND included an
change of conditions/extension application WITH the inland PR application, ensuring that it is received by CIC prior to expiration of your original work permit. This, in part, is what the CIC agent was talking about - unfortunately (but not surprisingly), her information was a bit misleading. She neglected to ascertain whether you had a work permit that made you eligible to continue workingi - and she didn't tell you that if you don't have that, you'll wait at least six months
without the ability to work while they get around to assessing your for first stage approval. Also, the 30 days prior is not a hard and fast rule. What has to happen is the extension application HAS to be
received by CIC before your status expires - so you could FedEx overnight it to them two days prior and still be fine.
That said - a holiday working visa is not eligible to be extended. So applying via the inland PR process may or may not be of advantage to you. It depends on whether you're from a visa-exempt or non-visa-exempt country, and which overseas visa office would be processing your file if you were to elect to apply outland (yes, you can still apply outland even if you're wanting to stay in Canada during processing).
getaround is right in that you can apply, with an inland PR application, to extend your status with an open work permit. The requirement for your inland PR application AND your extension application to be received by CIC prior to expiration of your holiday working visa still applies. But you'd wait at least six months for first stage approval - after which you'd be issued the open work permit - and then another 6-12 months to finalize the PR ap. If you apply outland, you can still apply separately to extend your status as a visitor - based on your marriage - and you could possibly (depending on the processing timeline for your particular visa office) see your PR finalized in about the same time frame as it would normally take the inland PR process to get you to first stage approval and an open work permit. Of course, with landed status, you don't need a work permit anymore.
So - in order to advise, we need more info about which country you're from so we'll know about how long you could expect to wait for finalization of an outland ap - that will determine whether applying inland and waiting longer for PR in order to be able to work sooner is a reasonable alternative. There are things you give up when you apply inland - like the right to appeal a refusal and the ability to leave Canada during processing. If you are not present and residing in Canada with your sponsor/spouse, you cannot be approved - so if you leave and are not readmitted, you forfeit your inland application.