Your mileage may vary, but this is in fact what we did.
We cancelled the lease for our Ateca 8 months prior to it running out naturally – mainly due to the concern that the Golf GTE gets removed from the scheme. We cancelled, and immediately ordered the Golf (which got removed a few weeks later, so best decision). We had to pay £50 cancellation fee, and we got a “marker” on our account so we can’t do this all the time.
But: because we’ve been waiting for over 14 months now, we’re beyond the original lease timeframe – which means that our £50 get refunded, the marker gets removed and we get full GCB (plus pro rata for the required extension so far). Basically, it’s like we never cancelled early.
I don’t know if that’s viable for everyone, but that’s how we managed to order around 8 months prior to our original lease running out, without repercussions (due to the fact that the car’s taking so long).
Prior: SEAT Ateca Xcellence Lux 1.5 TSI DSG MY19, VW Golf GTE PHEV DSG MY23
Current: Hyundai Ioniq 6 Ultimate
Next: we'll see what's available in 2028.