8 weeks. It should have been much quicker, but it wasn't. I even had to get additional short term insurance for the final few weeks which was an expensive annoyance.
The actual handover was smooth though, the guy who collected it inspected it and signed it off on the driveway and was sensible about reasonable wear and tear (light stone chips, scuffed seat covers) and clearly couldn't be bothered to look too closely at interior plastic (I had a missing bit around the boot latch that had fallen off somewhere).
Of course it got unpleasant a few months later when Santander threatened me with legal action over the outstanding debt in a letter on a Friday and their helpline doesn't run at weekends and has a massive queue when it does. After I phoned up in a panic and waited for 2 hours in a queue they very unsympathetically informed me that it was a letter sent by mistake and I did not in fact owe them anything. They offered a grudging apology and admission of fault after I made an official complaint, but didn't offer to compensate me for my time or distress.
I've made a complaint to the financial ombudsman.
So yeah, everything is fine with Santander unless you want something done in a reasonable time frame and don't want to be mistakenly threatened with court action at a later date.