Thanks, you guys!

In the end I did make it hollow (stuffed with newspaper underneath a layer of aluminium foil) - why is it things always come to you just after you've decided to ask for help?!

It was still a bit of a pain - it wasn't sticking together very well and by that point my patience was at an all-time low!
But, in the end I just about finished it with the dough I had, and it's in the oven as we speak.
When I put it in it was still a bit bumpy from trying to hold it without leaving marks, and there were still lines around the pieces of dough I'd stuck over the top. I was worried that it was going to stretch and leave gaps where you could see the stuffing or that the added pieces would fall off, but I checked it just now and the lines have diappeared and it's all stuck together quite nicely.
Plus, the kitchen is finally flour-free and spotless!

So, thanks.