Is it something i am doing wrong? I ice my cake with buttercream and put it in the fridge for a bit and then I put my fondant on, but after a little while my fondant starts to bulge out on the side on the cake like there is a big air bubble under the fondant and it starts to crack, any help or tips would be great please

Hmm.... I never put my cakes in the fridge before covering in fondant. Maybe the difference in temperature causes the bubbling? After frosting a cake in buttercream, I wait for it to crust and then cover with fondant without any problems.

Is this house too warm? The fondant will bubble like that if it's too warm. If it's warm and/or humid, try putting a fan on the cake and keep checking it, smoothing every couple minutes until the fondant begins to setup.

Also, I find that if I bake and cover in fondant the same day I get that happening sometimes. I try to let my cakes sit out overnight so that all gases can escape, then put on my bc and fondant.

Did you let your cakes settle?

Here's a link to Leah_s "trick" post:

http://cakecentral.com/cake-decorating-ftopict-633571-.html

HTH