Really big plain iced cake for party!

[Notthisyear]

Hello,
Thinking a cake I can decorate myself with stuff from eBay is the way to go for ds' birthday party, but can't find any supermarkets online selling such a cake that isn't fruit. I'm sure I've done this in the past!
Obviously I can and will trawl round all the shops, just though someone might be able to point me in the right direction - I don't want to buy it online, just know where to look so I can spend time on party bags instead
Have invited 40, your guess is as good as mine about how many will come!

Asda has a plan sponge cake meant for putting photos on you can just buy plain. It's rectangular though.

M&S do as election of plain iced cakes

Thanks for those ideas. I'd heard of the Asda one but assumed I'd have to put a photo on, which I don't really want! Will check them out.
It's harder to get a bigger one and I assume I'll end up throwing some of it out/eating it all week.

I would just ask a local bakery to bake you a plain iced rectangular sponge cake.

Costco do enormous ones really cheaply.

How about baking your own traybakes . They are really simple and taste so much better than shop bought. Just cover it with buttercream and sweeties and you will be on to a winner.

www.sweetsuccess.uk.com

These are quite good.

Second Costco ! Lovely cakes (you can opt for plain too ) . It's just a large slab of deliciousness for less than £15

Id say Costco but if you're not a member, the Asda one is great (you can def buy it plain, no photo)

You can order them online from Waitrose for collection in store. Various sizes and shapes.