Re: british pakistani/american pakistani culture
people from east coast may have problems adjusting to texas, thank god its not mississippi. Your cousins are absolutely incorrect we have a nice little group of brit-paks here in chicago that meets up every so often, aside from a coupe or two where both are brits who moved its a britpak married to a yankistani. no issues adjusting.
I thin the issue is less of a asian brit or a pak american, the issue is just as a brit can you adjust. and I am sorry to say cities in texas simply can not compare to London, they are mostly spread out suburbia and lack personality as cities, forget brits, as my newyorker pals went to dallas and sent an sos saying I need to get out of here etc. the lifestyle is different, its just not as cosmopolitan and multicultural as London, assuming you are in London (since that is the frame of reference most pakistanis have about UK)
you will do just fine, the places are fine, different yes, but they have their own pluses and minuses and as long as you are open to change, yo might miss some aspects of UK, you might find new things there that you could not find in UK and as a balance do just fine.
I am a Londoner, I love that city, its home no other place has the same feeling for me, but I like living in Chicago, love it in fact.