Hopefully a simple issue, the centre lock cap thing that secures the disc in place doesn’t leave enough room for me to tighten it with the tool I have Pic below of what I mean. Is there a different tool or lock cap?

The tools have different depths splines and different interior diameter. I’d try another lock ring tool.

You need an external spline lockring – it uses a Hollowtech II BB tool.

https://www.sjscycles.co.uk/hub-spares/shimano-deore-hbm618-front-left-lock-ring-washer-y24698030/

What sillyoldman says – you need a different lockring for a thru axle

As above, different lockring for 15mm hubs.

Ah great thanks, i’ll look for one in stock, cheers folks