I crewed an old maxi (77-foot) down that route in October '90. It still rates as the most character-building sail of my life. Expect and plan for a serious blow.
Stay well out of Biscay - don't cut the corner - make your Westing before you turn South. Don't believe that the Portugese Trades will cut in as you pass Bayona.
The Iberian High can stop the progress of depressions. So, if you're taking a battering from South Westerlies, don't assume the depression will move Eastwards briskly. GO WEST, YOUNG MAN and find the West/North West winds.