A European passport is perfect, an ancestry visa is acceptable for eg easyJet.
For the IR, I have heard good things about PAT in Bournemouth and I'd have a sniff around Bristol Flying Centre (I think it's called) for the IR. If you're not in the immediate position to jump to a flash job, they do charters etc and you need 700 hours to do that. (Some companies like 400 hours etc). Minor licence/insurance things I believe.
For the groundschool if you're not already enrolled in one in Oz, look at Bristol Ground School. Alex Whittingham and his team are brilliant.
Recruitment here is booming right now. (Note the 7-10 year cycle)
easyJet = 450 pilots next year.
Netjets Europe = 150+ pilots next year. (Just ordered 24 Dassault 7Xs)
Ryanair = no idea but it would be at least 200 pilots.
BA, Virgin Atlantic, Jet2, B Med, Thomsonfly (Britannia), Monarch, bmibaby all recruiting. (jets)
Turboprops. Flybe, BA Connect. All recruiting. Flybe takes direct entry captains. (Dash 8)
European companies. Air France, Air Berlin, etc.
Just about every bizjet operator such as Flexjet, TAG Aviation, Netjets (see above) are expanding.
Basicly, if you have 1,000-2,000 hours +, 500 hours turbine (ideally Dash 8, Saab etc) and above, there's a job here for you. If you have jet time, esp +20 tonnes, then there's a job here.
As for the flying?
Well, it isn't hard. SID-Airway-STAR-vectors-ILS for most airline type operations. Cat III for many operators. Weather is weather really. Seen more scary wx in Australia. Ok, it's a bit colder in winter but the countries that have the bad cold wx, they are equipped for it.
ATC is probably the biggest challenge. From the excitable Italians to the incomprehensible Russians (and metric) and the rapid fire Brits. Mountains are a bit higher too.
Probably the best move I (we) ever made career wise.