Thank you all for your import input, the deal is done I missed out on the wimsew it went for the full 800 so I have gone with the Adler £550 In it's favor as well as being much cheaper it's on a half table.
I don't even need to treck to the outer end of the country to collect it as my friend is up in the area and is collecting it for me.
I'm not worried about layers slipping because I have a quick and cheeky trick in how I tack my harness together before stitching double sided tape I often cut my straps with my Clint present and tack the harness around Thier dog, this method makes sure it will fit and when I'm actually sewing I can use it if bits don't want to stay lined up.
But now my real learning curve begins