It come time to buy a new PC and I have £1000 ready to spend.
However, I have no idea where to start!

Is £1000 even a reasonable budget or do I need to stretch to more?
How on earth do I know if I am getting my money's worth when I know little
about how much things are worth and I don't know where I can get
independent advice?
I have made my own PCs back in the late 90s and would be happy to do this
again, but I have no idea what the best set of components to buy might be.
Does anyone have any advice?