Flying does not affect pregnancy at all. There has never been any research conducted that has found this. It is perfectly safe to fly even at term. (provided you can fit in th seat

) The only reason why you can't fly at term is owing to the individual airline's policy on the gestational cut off which has more to do with their insurance than your health! The reason airlines have a cut off date for flying when pregnant is because they want to avoid the possibility of women going into labour or giving birth mid air as they do not have trained medical staff and equipment to deal with this and would have to make and emergency landing - can you imagine??? Yes some babies come early, yes some women have sudden rapid onset medical problems when pregnant but the vast majority do not. What the airline has weighed up is the likelihood of this happening statistically and have stipulated a cut off according to this measured risk and insurance costs should this happen (not just to yourself and your baby, they have a duty of care to you if they decide to fly you, but also all the compensation they would have to pay the other passengers should an emergency landing have to be made and the destinantion not reached on time)
If BA are happy to take you, you should be happy to fly provided you have no health issues and your doctor will confirm this. People get run over crossing the road and drop down dead in the street with heart attacks will that stop you going out in the street? Don't listen to the scare mongers, have a nice trip and enjoy Germany - the flight is only about 1 hour and a half (the time it takes some women living in the welsh mountains to get to their nearest hospital) so you will be absolutely fine. Just drink lots of water and exersice your legs somehow - just like any non-pregnant flyer.
Whilst abroad stay in air con as much as you can, drink loads and don't stand on your feet too long! Pregnancy is a state of being for most women not an illness and you are not an invalid. It is 34 degrees today here in Bulgaria and we have had many days at 40 degrees - it is HOT and hell! but you will not have to endure it for long and no the heat will not affect your baby only you might be a bit sick and tired of it - everything is hard work in the heat but you will manage.
As to insurance carry with you your E111 card - Germany is an EU member state afterall and has a duty to treat you - better care than the UK too I might add. Have fun and let us know how it all went
I have been worried about a lot of mis-information on this site. I know people are only trying to support you but sometimes you need proper professional advice. Opinions are opinions and as such have to be treated with scepticism much of the time. If you are still unsure or unhappy talk to your doctor your midwife, the airline, the insurance companies and value their advice more than other peoples irrational fears. Sorry not wanting to upset anyone.
I too am travelling by plane on Monday 32 weeks gestation and my flight is 4 hours long. My airline is Wizz Air, They cut off at 34 weeks. Very few babies come before 34 weeks. My last came at 36 weeks and I am not worried.