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Just to let you know you should get your UK tax back as it looks like you are non-UK resident and not performing a large amount of duties in the UK (I assume if you fly for a UK carrier then you'll occasionally be flying into the UK so will probably be taxed in the UK on a small percentage of your income).
As Grond mentions all you need to do is submit a tax return (which you can do online) - the deadline for submission for the tax year ended April 2007 is 31 Jan 2008 but as you are getting a reclaim you can submit later without penalty (although they will look at your return more closely if you do submit late). However you should submit earlier as there is no point the money being in the UK Government's account rather than your own!
You can also reduce the amount of UK tax that you pay over each month through PAYE by going onto a scheme known as the s690. This allows you to estimate the amount of UK duties you have and only have tax withheld on that percentage.
Lets say that you earn £4000 per month and about 10% of your flying & training is in the UK; currently you'll be having tax withheld on all of that and at the end of the year submit a UK tax return showing £48k salary with 10% in the UK so be taxed on only £4,800 - thus giving you a great big reclaim of tax.
Under s690 you say from the outset that you estimate about 10% of your duties will be in the UK so when you get your payslip you'll only have tax withheld on 10% of your salary and will therefore get more money each month. At the end of the year you submit your tax return showing your actual percentage of UK duties for the year and will either pay over or reclaim the difference between estimated and actual.
To go onto the s690 scheme you probably need to contact your HR / Payroll department and ask them; they then liaise with HMRC to sort it out for you.
Finally remember that as a German resident living in Germany you will almost definitely have to pay German tax on any of your salary that isn't liable to UK tax. This rule is relatively recent having only come into force in January 07 (before then you were in luck as Germany said that UK had taxing rights to your salary so they wouldn't tax you even though the UK didn't either!).
The way that this works now is that anything that the UK isn't taxing due to your non-residency becomes taxable in Germany. This probably doesn't include your UK personal allowance or non-taxable sector pay as the reason the UK isn't taxing these isn't due to your non-residency status but due to the UK's standard tax rules which are open to all UK citizens. Also note that this is any income that isn't liable to UK tax so if you didn't submit a UK tax return and paid UK tax on all of your salary then officially you would still have to pay German tax on this as well as most of your income isn't liable to UK tax - you have just been lazy about submitting a return!
Apologies for the long post - as you can see this is all very complicated so my best advice would be to pay someone a little bit of money to do it the first time and then you have a template to work from if you want to do it yourself. Given that the German tax system is stupidly complicated with deductions for everything under the sun most Germans use tax advisors anyway as they end up saving more tax than the advisor's fees cost them!