Hi, Fr alasdair, If you are interested in the Interior route, which goes from Viseu to Chaves, then to Verin in Spain and into Santiago on the Sanabres, you should scroll through this subforum:
https://www.caminodesantiago.me/community/forums/camino-portugues-interior-route.163/ There are several detailed foruom reports.
But since you say "from Porto", I think you are probably interested in the Central route. That is the more traditional Camino route, which goes up to Valenca do Minho and then over to Spain at Tui. There is also a subforum for blogs, etc. for that route here:
https://www.caminodesantiago.me/community/forums/camino-portugues-blogs-photo-albums.60/
I'm pretty sure you will find what you are looking for. One outstanding blog that describes Maggie's walk from Lisbon to Santiago is online at
https://magwood.me/my-caminos/camino-portuguese/
Bom caminho, Laurie