Tim

I cant count number of times I had the same issue. Even today my 4m old battery died (to be fair have not used the car for over 2 weeks due to cov and prior to that it was a 1.5mile round trip to shop), but at least it opened first time.
11 counterclockwise/ 3 clockwise is about right, and depending on how lucky/ unlucky you are it can take 15-20 mins to unlock (its like continuous and frustrating rocking).
This thread has good recommendations tried and tested by many members:
- WD40 
- Allen Key (I use padded garden glove as well)
- applying slightly more force counterclockwise
Solar battery charger may be a good purchase for the future.
Good luck!

Hi Tim - sorry to hear as I know the frustation (as went through it myself).  I don't think your passenger side door would be any issue here, as you'll be working on the driver's side with the key hole, also as you mention the fact that you can turn it at all.  Have you tried spraying some WD40/GT85 into the lock on the driver's side before trying with the allen key through the top of the key for leverage?  Might want to leave it for a few hours after applying too, but work it in a little.  Just to confirm, you are turning it toward the rear of the car?

No problem.  You want to turn toward the back of the car to open the door.  In your case with LHD that would be turning clockwise (sounds like you're doing the opposite?).
Try and get some WD40 or GT85....frustrating with the shops closed, maybe a neighbour near by or a friend(??)
I know how you're describing the feel of the movement of the key (as I felt it by hand), once I have the greater leverage with a drill bit (instead of Allen key in my case) through it it just easily turned that bit extra to unlock.  Again, this was after applying GT85.
Thinking ahead a little, once you have the car open do you have a way to get a mains powered charger to it or another car to attempt to jump it?  Alternatively you can take the battery out to charge, but I appreciate it's more hassle.

If it helps, you can see a LHD car being opened here (turning the key clockwise to the back of the car) - https://youtu.be/KCgQdI8UddU?t=88
Keep in mind it looks easy as that car's battery is fine (it's a video about the fob battery being dead) and the central locking with power is very different to you manually turning it with a tiny key head (by the design!) and a lock that probably hasn't been used before.

See how it goes with the WD40.  He hardly has to turn the key in that video as the powered central locking kicks in.  I was just sharing it to confirm the direction for you.
Don't try your portable battery jumper, you will only set off the alarm for a few seconds and frustrate yourself and anyone close by 😎  Read a bit further back in this thread and you'll see I had the same thought.  When the battery is completely dead it is simply not enough to bring it back to life, it needs a charge.  The car seems to also think it's under attack with the battery booster pack approach so momentarily while it lasts uses the power to activate the alarm.  Sorry to be the bearer of bad news, but hopefully saving you some effort there.