Speedo needle doing a dance!!

[His Dudeness]

Lol defo speedo. I'm new to all this and not very hands on but want to try wots within my capability. If it's a dodgy wire are they easy to fit??

It's easy to fix a wire but you have to find where the problem is first which could be a pain. Think opening the loom and going through the earths. I'd say just live with it for now, see if it settles down. If it keeps going crazy then think about fixing it. If you're going to fix it you'd need a soldering iron, decent solder, heat shrink and loom wrap.