Im making a cake and covering it with fondant (sugar paste) could I use Swiss meringue butter cream to fill and cover the cake prior to covering it in fondant?

You can use swiss meringue or any other BC before covering in fondant. I like to use a thin coating of BC so it doesn't smoosh out the bottom.

I tried this one time and the fondant was gooey at the time of cutting the cake. I used MMF and don't know if it works better with Satin Ice or other brand of fondant. For covering my cakes with fondant I am sticking with a thin coat of sugar powder based buttercream.

I do it all the time.. never had an issue with fondant being soggy. I use Michele Foster's recipe for fondant.. works everytime. And I use a normal layer of BC under the fondant as opposed to a thin layer. Just chill your cake for a bit before you cover it and you won't have any shifting of the icing while you smooth your fondant.

ok thanks for the help, i use regalice fondant (its a UK brand i think).
i hope it works ok, im making the cake in class as a project.