Hi,

We've been getting some quotes for supply & installing a small set of
external French doors that lead to our garden, but they seem a bit pricey at
around £1400-1500.
After a trip to B&Q I see you can pick up a ready-made set that would suit
us for around 400...which implies a installation cost in our quotes of
around £1000, which hurts in the wallet area.

I'm fairly competent on the diy front, so I was wondering if this something
that I could reasonably do myself (perhaps with another set of hands to
assist)?

Which then leads to my next question... the house is timber framed and the
doors would sit in a space of which the top part is currently occupied by a
window. I'd obviously need to knock out the bottom section (mostly
plasterboard), but how do I seal the sides? The outer skin of the building
appears to be a layer of some kind of black sheeting covered with rendering.
What is the skin made of?

TIA

Phil