You can sit part1 in the UK but must trvl stateside to sit the practical/oral.
I got the computerised part1 completed about 2yrs ago at Staverton Aerodrome in Glouchestire. I think it was called the American Airman Testing centre or something like that.
Overall very good & professional.
They do run trng courses but i'd suggest self study with one of the Big Red Books from Gliem.
Rgds
DX Boy