I refill when the ‘estimated range’ gets to c. 100 miles (it’s also Golf). The previous two (Astra GTC’s) just had a needle indicator and I’d refuel when it hit 1/4 full.
Most refills are £30 because most of my trips are fairly local. When I’m setting off for Oxford to visit the peeps I’ll fill the tank.
On a second point, in the nine years I’ve been driving I have only ever used two garages – one local and one on the coast. They both have plenty of space so I can pull up by the pump far enough away to fully open the door and get out (filler cap always having been being on the drivers side) without blocking access for other vehicles.