My friend son is on a very tight budget so she has asked me to make his cake, ive never done a wedding cake as im still a learner, i normally use the austrailian mudcake recipe on here as thats what they want, but i donot know the shelf life of it or a buttercream type icing thatwill last awhile too under fondant, they want a light blue 2 tier cake with dark blue arum lillies on the bottom of the 3 corners of the cake as the top tier will be on pillars & will sit on the corner of the bottom cake as they do not want it to be in the middle of the cake, i have no idea how to arrange these lillie or what size lillie cutter to use and what leaf cutter to use for this lillie or even how many to make each corner so that it looks nice, on the top tier they want me to model 2 doves holding silver rings which i have no tutorial for but i think two doves just sitting on cake would be a bit boaring, does anyone have any ideas or drawings that could give me any help. also i donot know what two shade colour name of the gel colours to get of blue, they wanted a lite type of baby blue and a dark or royal blue, but she said shell leave the rest up to me on design, and for around the eddging i cannot pipe any ideas please, my big pan size is 35cmx31cm. the weddings in january so i have to learn how to make the flowers and birds, maybe i twine going from top tier to the bottom cake for the lillies might be ok, sorry to ask this but i am nervious in making this cake
thank you for all the help i can get

Would really like to help, but your wall of text is just too difficult to read for my old eyes....

I think your "friend" is asking an awful lot from you. When someone is on a really tight budget they shouldn't be able to dictate so many requests. Maybe you should do yourself the favor and tell them that you won't be able to do it.

On Youtube there is a great tutorial on how to made calla lilies (aka arum lillies) by Edna (Designmeacake.com). She uses heart cutters to make the lillies, really simple. I can't help with the fondant side of things because I have yet covered a cake in fondant, I ice my cakes with buttercream. As for borders since you said you can't pipe how about ribbon? As for the blue I would get Americolors Royal Blue and for the baby blue just add less colouring to get a lighter shade. For the dark blue lillies Americolors Navy Blue. As for the doves I would buy figurines, go on ebay and have a search, include the price of the doves in the price of the cake. You will save yourself a lot of headaches buying a pair of figurines rather than trying to make them. You could have a go and use the figurines as a back up. I hope I have helped you If you need to bouce more ideas feel free to message me. By the way don't let the couple's tight budget affect your pricing of the cake. Quote them a price and if they say it's too much then offer simpler cheaper alternatives. Don't give them what they want at a cheaper rate because then you are out of pocket.

about the wall of tex i am a bit nervious about this cake was just wanting to know if anyone could help on what are the names of the 2 shades of blue to buy, and how to make calla lillies and doves, i did say no and told her to get a perfesonal to do it but i guess they cannot afford what they want made, at least i have til january to sort of find things out thank you

You can use any color blue for this. Just use more of the color in the lilies and less in the icing to acheive light & dark blue.

But there's so much more to it than this! An idea for you is to purchase the lilies and the doves already made. You can buy white ones and color them.

Mud cake has a pretty reasonable shelf life.. saying that, mud cake tastes better when it has actually had time to rest for a few days after been baked- so that is one thing on your side You could actually try a ganache under your fondant (google ganache crumb coat for tips) As for your lilies, I say google as much as possible - just type calla lilies (or arum lillies) cake designs and get inspired by other peoples designs. Google video tutorials if you want to give sugarpaste flowers a go yourself.. or as someone else suggested you could always buy them.. maybe purchase white ones and paint them the desired color?! As for the boarder.. I think making a fondant ribbon would be a charming alternative.. you'll have more control and it will probably balance the cake design nicely with the doves and the lilies.
Good luck and have fun with it