I invested a giant 1k into Just Park when it was on Crowdcube in 2015. At the time it wasn't EIS eligible but they were 'looking into it'.
Fast forward 2 years and they finally confirmed that EIS relief was available - Yay!

I'm tying myself in knots trying to follow the guidance on how to claim the relief though. The EIS form they sent through (dated Aug 17) states the date of issue of the shares as May 15. Does this mean I need to "amend" my already submitted tax return for FY 15/16 - perhaps online or by returning the physical claim form attached to the EIS form to HMRC? How does that work exactly?

It would be easier to just include in FY 16/17, the tax return for which I am in the process of completing, but I suspect that would be too easy?