A clean slate's hard graft Sally but a lot of fun! I've done a couple of gardens from scratch. Fortunately they weren't jungles, just empty and pretty sterile, but I've had experience of a large, neglected one as well. It's worth it when you start seeing some reward for your efforts.
Keep us updated with pix as you go along, and there will always be lots of help, ideas and advice here to keep you motivated as well. There's also a seed swap thread and many of us swap plants and cuttings so that can help get borders filled!