I am presuming that the worktop hasnt been fitted yet.
After cutting it a few mm oversize with a plunge saw I would clamp or screw a wide batten to the underneath of the worktop and using a top bearing guided cutter in my router I would cut from right hand side to the middle. Then turn the...
I have seen what you describe several times and always assumed it was just a cheap bodge. I can't see why, once you have taken out your old window, you shouldn't brick up to the lintel.
I presume you're notifying your LABC and that they will be able to advise.
http://www.directa.co.uk/site/scripts/product_browse.php?product_id=2973&category_id=457
or
http://www.mysupermarket.co.uk/asda-compare-prices/Light_Bulbs_And_Candles/Swan_Fluid_100ml.html
or
http://www.decoratingdirect.co.uk/viewprod/b/BIRCELT/
Check on a small area first and use PPE and...
I've never fitted plastic windows but if you take out the old sash box frame out and then fit a double glazed sash box frame in it is deeper and will stick out into the room. You then have to pack out the architraves. Is this what you meant?