Agree with missing out Scillies but head straight to the Rias bajos and enjoy them before heading north, turning the corner and exploring some of the northern coast although you will need to anchor or to go in marinas. I think from N.Spain and giving yourself a week or a little more to get back...
As mentioned by other people, you can moor and raft ukp alongside in front of the pub (watch the drop) Don't any of crew know anyone in the PYC to beg a favour from on their pontoon to raft up to. The pontoons further up past the Bridge are NOT public.
Don't know what tides are for your dates but there can be be high vertical drops with a very nasty end if not careful. The wild beast show that is the Gosport ferry must be considered against this - but considering you could be one of the the beasts - then it's your pick.
Have a look at SAMM website and consider joining. (Sailing Association Mar Menor) - active club - they do regular cruises in company to Balaerics, often for 2 weeks and normally on the hook - there are cruising mobo and racing groups
Oh by the way wherever"here" is sounds like a load of...
Premier marinas do summer and winter berthing rates without taking out annual contract (prices not out yet)
Plenty of moorings and half tide moorings available for bilgers
Keep it under 10m if in marina, price band changes.
Plenty of boats that size with good headroom
Join a club
Don't people use adequate fendering these days ? Always amazes me that some have plenty out on the their berthing side but a solitary (usually small) one, if any, on the other where damage to others is going to happen - I always have plenty out both sides giving adequate protection to both sides...