No, you can only use British stamps for mail posted in London. (You wouldn't expect to be able to use a stamp from a different country on a letter mailed in the USA.)
1 oz letter to UK is .94
That is what the US issues stamps for, so that you can send mail to anyplace in the world.
yes- the rate is 98 cents for an ordinary letter of no more than one ounce.
what the price to mail letter to
how many forever stamps = .94
5
No, the postman will ignore it. Go get stamps.
typicaly 2 stamps
maybe 2 0r 3 stamps
Stamps show that you have paid the money to have the letter delivered.
No, you must use US postage stamps.
depends how heavy the letter is