Ivor often recommends the FRITZ Box. I see that the ata/router sells
for about £80 ( or is it cheaper elsewhere?)

I am only familiar with the Sipuras. What I'd be interested to know is
whether the Fritz Box has a dial plan similar to the Sipuras or does
it use some other method of determining routing.
I checked out the pdf but, unless I missed it (it is a long document
to go through), I didn't see the relevant bit.

Further, is there provision for a number of outgoing providers or is
it limited to the same one used as incoming for a given line?

Remove 'no_spam_' from email address.