Have you thought about checking out that GT100 at a Screwfix store?
The manufacturer "Time" replied to some Questions with
We would not recommend this for outside use without a conduit to protect the cable but if in any doubt please contact a qualified electrician.
and that is is not double-screened !!!
= Avoid it, I think.
(They did state it was solid copper core, though).
https://www.toolstation.com/doncaster-cables-coaxial-satellite-cable-ct100/p76103 is not all copper either. (Copper clad aluminium foil and braid). See https://www.doncastercables.com/cab...Security/Satellite-TV-Coaxial-Cable-as-CT100/
So another one to avoid.
RG6 is too often copper clad steel core to be recommended for any use to diy people whatsoever in my view. CAI spec RG6 has to be copper clad steel! (Though if one can find a supplier of all copper foam filled RG6 it'll be excellent stuff for TV and satellite use).
Amazon sellers supply Webro WF100. CPC Farnell sell it too with fast delivery usually.
CAI certified type 100 cable must be all copper or aluminium foil with tin-plated copper braid to meet the CAI spec. https://www.cai.org.uk/index.php/co.../cable-certification/110-cai-certified-cables I'd prefer all copper though, so have a stockpile of WF100 in my garage.