Tony,
Why not contact the OCC Port officers directly, for first hand info? I know that Lagos is much used by overwintering yachts.
PortugalLagos
Terry O 'Brien, Rua de Santo Amaro, 7A-2C, Lagos, Algarve, 8600-708, Portugal.
Tel. Home: +351 282 769 495, Mobile: +351 964 872 962,
Email: tmob@sapo.pt
Lagos
Ingrid Fortunato, Marina de Lagos, Edificio da Administracao, Sitio da Ponte, Lagos, 8600-315, Portugal.
Tel. Office: +351 282 770 210, Fax: +351 282 770 219
Email: ifortunato@marlagos.pt
How about the small marina, Puerto Gelves, way up the River Guadalquivir in Seville? A great city to spend time in, and transport to/from UK should be easy. Check out
NoonsiteThe River Guadiana is much used for overwintering, too, but there have been flash floods, and I 'd be a bit concerned about that.