In a normal GLM is the dispersion parameter equal to the marginal variance? I am trying to compare variances across models, am i correct in thinking that in a normal GLM the variance is equal to the dispersion parameter. So is my dispersion parameter is 40.1 my variance is the same value?

Yes, in a normal generalized linear model (GLM) the dispersion parameter and the variance are the same thing.
If you are fitting a normal GLM with identity link (which is the default) then you may as well use lm() instead of glm() because it does exactly the same fit but with output in the familiar linear model form.
