Good Morning guys (I'm in Australia), and first of all:
THANK YOU VERY MUCH EVERYONE. I didn't expect such a great response. I've now got a much better insight into what's involved.
Regarding assembly I think I'm leaning more towards a low quantity test run of boards and FOR NOW I'll put the components on myself. If more serious interest in my little board is shown as word gets around, then I can look into getting the assembly done for me too. I feel like I'll be more of a hassle to a manufacturer at present if I go the assembly route.
I'll have to do some research on soldering SMD components. Some say that once you get the hang of it you'll find it easier and quicker than through hole components. If that turns out to be true I'll redesign the board with SMD parts, which will also reduce the size. And having a professionally made board with solder mask should help greatly.
Making the PCB itself is actually quite easy for me but the hole drilling is the hard bit. I ended up mounting an electric die grinder on my 2400 x 1500 CNC plasma table and drilled the holes that way, talk about shooting a fly with a bazooka. Too much hassle overall when I look at the pictures of the professionally made boards, they look beautiful.
It's quite a simple board and as a hobbyist I've made everything big and chunky, much bigger than necessary. For a PCB manufacturer I think they won't come much simpler / easier, no fine tolerances here.
Keith.