Well, the claw-thingie arrived this morning and I've managed to remove the filter. Took a 2 foot breaker bar to loosen it!
Next question:
I changed the auto box fluid and filter too. When I checked the handbook, it said 4.6 auto box capacity was 11 litres, but when I put 7 in, it filled the gearbox dipstick tube completely! Necessitating diving underneath again to drain off some dextron 3. I've cycled the box through all gears, and checked the level when ticking over, but can't see how 11 litres will fit in. And I've bought 15 litres of the stuff too! Any ideas?