Thanks for all the advice.
That tool for the grinder looks good. I will order one of those.
I have redone the sections that I wasn't happy with. Cutting long and grinding to the marked line works well.
I am only tacking at the moment and practising fully welding on offcuts as I go. One of the reasons I wanted to do the whole thing myself was to learn new skills like this so its good to get advice on here and see my work improving.
Thanks guys.