I also want to say thanks for all the info. and advice I gleaned on here about the trip. We'd never done it before and all advice was very welcome. We also acted on a lot of it, especially when it came to routes and places to stay, so thanks to all.
We arrived in St Malo on the Tuesday at 8.30 am, and by 11.00am we were having a lovely breakfast in a beautiful little village called Derval near Chateaubriant and stocking up for a picnic at the little shops we'd have later on in the day.
Our overnight stay was at Royan as suggested here, a nice hotel was found on the esplanade via Booking.com (what a great app) and we had a nice overnighter there.........shame everything was closed for the season though. The town was like a ghost town when we ventured out

Next night was another tip from on here, we found a simply beautiful typical style hotel overlooking the bay at Saint Jean de Luz, a really stunning location and one I'd love to spend more time in.
Final stop was in the Basque town of Brinas in La Rioja. Again it was totally beautiful town sitting next to the Rio Ebro, so tranquil and quiet. Hotel was amazing and the evening meal in the local Basque restaurant was memorable.
A fitting finale before the 9 hour drive the next day to our place.
The trip went perfectly apart from one satnav glitch on the first day that sent us miles off course and caused a minor bun fight in the car

Contrary though to what I was told I thought the French main roads were far busier than I was led to believe. I simply could not engage cruise control until I got on to the Burgos-Granada stretch such was the intensity and volume of traffic, mainly HGV's.
The stay at the house was very nice apart from suffering 2 separate punctures which justified the decision to take the spare.
Also as well as being fortunate to have gone in the car this time instead of Monarch we were also glad we were in it as our Spanish vehicle we have there had obviously had some "furry friends" camping in it for a few months, what a job to clean that out.......I don't think the OH would have been too keen on using it after that!!
Briefly the journey home consisted of 3, but more equally spaced legs than we did coming to the place.
We made a first stop at Aranda de Dueno, south of Burgos, pushing on to a fabulous experience staying with a French couple who advertise their stunning rural home on booking.com. A total pig to find and even worse to get out of but it was worth it for the memories. A totally superb stay in idylic surroundings with a stunning Table d'hote we had with them. The chap was also in to classic cars and hifi like myself and we got on like a house on fire. What a night.
Last leg was to Ouisterham near Caen for the ferry home. We stayed at a hotel not 300 metres from the port. Not the best of the holiday but brilliant for the 7.00am check in we had for the ferry.
One sinister point there though which the locals are very worried about was the recent arrival of "asylum seekers", however that's another story.
I was sad not to have more time there as I said I'd like to see some of the WW2 history there. We did cross the "new" Pegasus bridge and we made a point of visiting Sword beach, a truly thought provoking experience.
Mrs DA was touched by all of this too and we have vowed to do a week there very shortly, dedicated to seeing more.
All in all a superb and memorable trip with so many weird experiences along the way.........not least the day we had 32 degrees in Madrid an -1 degree not 18 hours later further down the road, incredible.
Thanks again guys for your your input for this trip, it really made a difference and gave us a base plan.
Cheers
PS M50/R4 was a cracking piece of advice, thanks. As suggested we never saw more than 5 cars on the latter lol!!
PPS. Out of interest we covered 3,350 miles in total and car returned an incredible 53 mpg, fully loaded and not hanging around.