What do I think?
I would say forget about the 262 cockpit until you get enough room to do an expansion which covers the 262 going into active service with the Lufwaffe (high altitude recce plane hunting or something like that)
Within that same reasoning I would say forget about Southern England as well. Wait until you have some more room for that.
Finally, as far as other fighters go; I would hope for a Typhoon, but, planes like the Me 109G and FW 190A also have a place in what you're intending to design and build.