Ok, getting somewhere a bit closer, thanks for all the help.
So, charge controller and bluetooth module are fine for this.
Ultimately, I need a different, bigger panel and different batteries and a more efficient inverter. That will be a little further down the line and can easily be changed out as funds allow, probably a bit at a time.
For now, I can series wire the two 80w panels easily enough to get the system running, I'll look at a larger panel next and may have found some used 255w panels for a budget price. I'm building a box to contain all the other bits and get them wired up safely.
So, next thing is correctly wiring the batteries. Thanks for the diagrams, I can see what I was doing wrong now. Just have to change the stack orientations and wire correctly. Will do that today and post some pictures before I connect it all to check I don't let the magic smoke out.
For a fuse between panels and batteries, how about a small circuit breaker like this one (of a suitable rating). It would act as an isolation switch and fuse/breaker in one neat unit.
https://www.ebay.co.uk/itm/30-Amp-Amplifier-Car-Audio-Marine-Boat-Circuit-Breaker-Trip-Fuse-Switch-12V-24V/133075828989?_trkparms=aid%3D555018%26algo%3DPL.SIM%26ao%3D1%26asc%3D57477%26meid%3D8d6f836a7a2f431d923db681d8ebf0ce%26pid%3D100005%26rk%3D1%26rkt%3D12%26sd%3D171552429928%26itm%3D133075828989%26pg%3D2047675&_trksid=p2047675.c100005.m1851Roger, thanks for the link to the clamp meter, I'll pick one of those up as I only have a regular multimeter.
Batteries will need changing out for proper leisure batteries, that'll be next spring. The system is only in use from may to September, it runs the sand filter on a wood fired hot tub on our glamping site.
that leaves the inverter, any suggestions on a suitable model?
Thanks again.