Thanks both. It is a new frame (well new old stock - ex display).

I'll try re-greasing the pedal threads etc. Its kind of baffling me tbh. I thought these Ceramicspeed bearings would be much better than the bog standard DUB BB30 that SRAM make. I mean it feels and looks like its fitted super solidly - the noise is an odd one and not like other clicks I've had with bottom brackets before. Almost like a coiled spring type weird noise. It is definitely coming from that area. I thought maybe the spacers or the pre-load tensioner but its as per the instructions so I don't see why.

And why would this start up after 20 miles / 10 miles respectively? new bke days are meant to be exciting and this is turning into a nightmare.