I got myself a pair of David Clark H10-13.4 with gel earseals from Headset Services, tel 01273 234 181. They also sell Peltor, Sennheiser and other headset makes. If you give them a call they can advise you on which headset will be best for you. I was wearing the David Clark headset once for three hours in one go and found them very comfortable and I didn't have any problems with wearing glasses.
If you have just started training for your licence you might also have to consider what type of headsets your instructor uses. It seems that some headsets don't work very well together with other headset types.
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