I'm not an expert, I have just done this for the first time, I too was bricking it but it turned out to be relatively straightforward. I watched a few videos on youtube about window fitting which gave me all the info I needed. One tip with fitting windows, get a air or electrically powered mastic gun, that glue is very heavy going by hand. I found it more difficult to get a decent instruction on the carpets; the best info I found in hindsight was someone who said "it's easy!"
I did the windows and carpet a side at a time on the same day. First job bask the outside of the van, then drill the corners of the panels from the inside out. Grind out the internal strengtheners to allow the jigsaw to pass. Mark out the outside of the van between the drill holes, then mask up to the lines to give the maximum protection to the paint. Finally I cut out the panels with a jigsaw with a good quality sheet metal blade (Bosch T118A). Filled the edges smooth and flat and painted the edges with a cold galvanizing paint then sprayed some clear lacquer to seal it.
Once dry I started on the carpeting, I got 10M of super stretch carpet from Mega Van Mats as a kit with glue. For the sides I started by cleaning the metalwork with IPA then cut a 3m (SWB) length of carpet. I laid the carpet out on a tarpaulin and sprayed one half with the glue; then I went in the van and sprayed the front half of that. With help from my wife we carried the carpet to the van and held it up in place making sure I left enough at the edges to go around the B post and the roof rail. First I contacted the roof rail, then down the B post at the same time pulling down any slack to avoid creases. Then down the C post and the bottom window rail to about halfway to the floor. Then we folded the carpet back on itself so I could spray the remaining carpet and van sides as far as just short of the D post, I contacted the top then started working down with my wife keeping the carpet away from the wheel arch while I worked my way down. When you hit the wheel arch it's just a matter of pulling the carpet down and away from where you are working, if it gets tight use a hair drier to warm the carpet slightly to let it stretch more easily. Finally spray the rest of the carpet and D post (doors seals removed on that post) are finish off. Job done, and way easier than it sounds, just plan the moves and do a quick dry run to make sure everything is in place before you apply glue. A pair of metal handled scissors makes a good former to get the carpet into the curves.
Excess carpet was cut away and window edge trim applied, an old credit card helps get the trim and door seals over the carpet. Now apply the activator and primer as per the instructions that come with the window glue and apply the glue (cut the nozzle halfway down with a Veecut that is about 12mm high) Then hold the gun at 90 degrees and the vee cut trailing and go smoothly leaving a bead of glue high enough to clear the edge trim (remember that powered mastic gun? I bought a Clarke air powered from Amazon for £19 a bargain!!!), stick the window on (get a pair of suction glass handles Ebay at £4.99 each) tape the window and job done
The only bit in addition was the piece above the rear doors, I cut that and glued in place overlapping the wall carpets which mask I off first. Then with a fresh Stanley blade and a rule cut through both carpets, then peeled off the wall carpet waste from under the roof carpet good and resprayed glue to create an invisible butt join
Don't be afraid, be accurate with your cutting and think about the steps first, it really is very easy and a good looking job is very achievable
. Lots of help available from good peeps on here, including Trade Members. I would advise you to read through a Trade Member's thread of a vehicle being lined out. You can find it at the discussion area "Interiors, Seating, Lining" under the thread on page 3 "@Thoggs lining as it happens". The firm, 
