Hiya, We did a 4 tier cheese cake for ours, the local shop quoted us about £500, it is entirely do-able yourself if you want to give it a bash, it's lots of fun to do and cost us about £200'ish.
Our large Sainsbury's were fab, we went to the cheese counter they gave my husband I I samples of about 20 or so different cheeses, we had a large stilton, umm the one with 3 colours (three counties?) Brie and a goats cheese on top. They ordered them about 6 weeks before the wedding and we picked up a few days before (very heavy) they gave us all of the diameters for the cheeses.
We went to a local cake shop and hired a 4 tier wedding cake stand and bought 4 round wooden chopping boards, just cheapy one's and made sure they all fitted in the slots, off centre stands were the best we decided so it was easier for guests to serve themselves without having to take it to pieces.
We ordered a couple of nice wooden mice from the internet for the top, a pack of ummm what is the fruit that looks like small orange cherry tomatoes with leaves (stupid emotion), some nice flowers to match your theme dark red & orange look nice and fill the gaps with these, and voila.
I would second what others have said about a few small sweet cakes for the younger guest did turn out to be the right thing to do.
Hth and have fun cheese shopping yum yum. x