Strongly recommend you try and get to a decent pilot shop and spend
plenty of time trying on the various contenders. Don't just buy brand X because everybody else does - headsets are very personal things and what may suit one person may be most uncomfortable for somebody else.
With a budget of £200 you will be looking at passive headsets (ie they don't use clever electronics to reduce noise) so the effectiveness of the ear seal is important - especially with glasses. Avoid headsets which have a high clamping pressure to achieve the seal, look for comfort and gel-filled or soft foam seals.
Bear in mind that a plastic seal next to your skin will be sweaty in warm weather, you can get cotton covers which help - but at the cost of reducing the effectiveness of the seal. Some headsets have soft leather over soft foam options (Sennheiser and I believe Beyer), which is my personal preference, but you need to decide which you prefer.
Once you have decided on a specific headset, there is the question of a source - eBay is good for secondhand ones as long as you don't get carried away with the bidding and your local club noticeboard is a possibility too. Alternatively, with the dollar at nearly $2=£1 it may be worth looking at a supplier in the USA, especially if you or a friend are visiting, otherwise add about 20% to the delivered price for import duty etc.
For the record, I use a Sennheiser HME100 SE-2 headset - the SE being the special edition with soft leather ear seals and a bit more headband padding. I'm perfectly happy with that, but of course you may much prefer something entirely different. Final advice - don't rush the decision
