I am a prospective student who has been accepted to math and physics. I was wondering about undergrad summer research. Is there anyone on this forum who has done undergrad research? How easy or hard is it to get a summer position doing undergrad research?

In the math department, you need at least a 10 average to get an NSERC position. You usually can do this by the end of your second year. You must approach a professor and discuss the possibilities with them. If they agree to fill out an application for you, then I think you will usually get the position.

I haven not done any myself but I have had quite a few friends who have done their senior thesis (in Bio however). Doing a thesis or senior project is the primary means to do research. Some profs will have you work in the summer before your thesis so you are more familiar with your project/techniques. A lucky few are able to do summer research after second year (I have never heard of anybody doing it after first), but this is very rare and I cant speak for math and physics. It mostly comes down to how much grant money they have left, space in a lab, chances of you getting an NSERC grant.
To sum it up, it is possible to do research in the summer but very unlikely. The only people I have known to do it have used family connections getting them a spot at another university, and it wasn't research so much as helping out around the lab.

lots of students in Physics get them but it all depends on keeping your marks up. I know a lot of people who went through physics who've got them each summer.

Physics department garantee you a NSERC position after first year if you get 12 on either physics 1b03, 1bb3 or 1ba3 and are going into honours physics. So if you are interested in physics and doing research in the field, honours physics is a way to go! (I'm a first year physical science student going into med phys (well... hopefully) next year)