No need for the tail. FWIW
MPB tend to be careless with their checking of used kit - I bought a lens from them & it was non-functional, as was the replacement they sent. I ended up buying elsewhere, (and that lens had cosmetic damage, but worked fine).
For an original A7 with that on the screen I'd conside Nand's £200-£250 reasonable. Last spring I was considering an original A7 from
LCE for £350 in excellent condition, but ended up getting an A7III.
FWIW I moved from Nikon to Sony last year, and found Nikon lenses & adapters weren't *great* to use compared to being on a Nikon body. I'd recommend turning off the 'in focus' highlights and instead set up a button to zoom in for focussing manually so you can get it right. The other thing is that a lot of adapters are a bit slack, allowing some lens rotation & even wobble, which is simply poor.