Google Earth shows a distance of about 2,400NM (from the southern tip of Greece, via Gibraltar & Biscay). So non-stop sailing @ 5 knots = 480 hours or 20 days. So maybe somewhere between that and triple that to allow for stops, weather windows, adverse currents and winds, etc.
The new owner of our bav 36 has just sailed her the other way, ie from Lowestoft to Greece in 57 days. They covered a total of 2772 nautical miles in no particular rush, and stopped over in many places on the way. To see their trip in detail, see www.prophecygoeseast.com. Good read and nice pics too.
I think it is harder coming back, ie westbound through the med. Prevailing winds tend to be westerly, so over 60 would be a fair guess. Having said that, MaxSea comes up with 20days not counting any time stopped over. Legs (except Biscay) kept to 150 average.
[/ QUOTE ]2698 miles from Athens to Portsmouth (direct across biscay). 568 hrs cruising at avg 5kt would take the guts of a month non-stop assuming some rest days, weather breaks, odd overnight stop. For pleasure probably more enjoyable over two months.
I sailed (actually motored most of the way) my 33 footer back from Preveza to Douarnenez in May/June this year and it took 6 weeks. A full week of which was spent waiting for decent waether in Cadiz and 3 days in Sardinia. We also took 2 x 1 day rest breaks and about 6 night stops.
With just 2 of us aboard it was quite hard work. We experienced few strong winds but progress was often difficult due to big swells from distant gales, both in the Med and Atlantic.
With a 38 footer you will be a little quicker but you will still need some luck to do the trip in less than 5 weeks.
Twice as long as you plan - everything is against you at this time of year - especially coming up North - Uphill most of the way and a bumpy time in Biscay even if you time it to a SW'lie across that bit.
Cold as well