Finally solved this problem and the solution was **really, really** simple.

I didn't realise that libtommath was actually in a Fedora repo somewhere, so on a whim (and out of frustration) decided to try this:

sudo dnf install libtommath

and bingo, I got a download! Tried recompiling, but it failed again, but further down in the programme.

Then I tried,

sudo dnf install libtommath-devel and got more code.

Tried to compile yet again and BINGO, my compile worked! Yaay for me.

However, I do think that these simple steps really **should** be included in the install procedure - would have saved a lot of grief on my part!

Thanks again to Paul Beach for your input.