You could try doubleglazingontheweb.co.uk, they cover your area and you can get an online quote.
They don't do the glass you specified, they work with pilkington... but you could try!
To give you an idea, the company that I work for could supply only (not install!) the first georgian bar sealed unit for £19.95 inc. VAT.
How much are they charging you for fitting?!
What glazing are you having? Are they toughened units? With any georgian bar etc?
Sounds a little over-priced if it is just standard clear glass.. the curving charges are approximately £20 maximum, install shouldn't cost more than about £25 a unit.. the units themselves about £60 each...