Some Royal Mail stamps have nominal value on it. There are 2 kinds of postage rate there: Economy and Standard. Economy is cheaper but slower than Standard. The rates are:
Economy: £1.26
Standard: £1.42
Most Royal Mail stamps you would probably encounter though would say 1st class and 2nd class. 1st class is currently 76p, and 2nd class is 65p. They are similar to the Forever stamp of US where the value of the stamp adjusts everytime there's a change in price. You can use multiple stamps to get the correct amount.

Oh awesome!
One last question if you don’t mind. I know that for a 1 ounce letter one global forever stamp is enough to get a SASE back to Canada from the USA, but how many Royal Mail stamps should I put on an SASE for shipping back to Canada from the UK?
Thanks so much for the help by the way

For UK stamps, I ordered from Philatelink. I ordered mine in bulk so it might sound expensive but I think it's worth if you're going to send to a lot of UK addresseses. I have only ordered from them once, and I haven't used all of it. (100 1st class stamps). Much easier than ordering in Royal Mail.

https://www.philatelink.co.uk/

I looked into that but because of the shipping (it’s $10 to Canada) it actually makes them more expensive than what I saw on amazon. I might go ahead and order US ones on Amazon. Are there any places that you know of where you can get Royal Mail stamps in Canada? There are 3 people that I want to eventually do that only have addresses in the UK

Thanks!

Do you buy the Global forever stamps from USPS's Ebay store? That's where I buy. If you want to send money instead, then it's better to be in US dollars.

Hello everyone!
I’m relatively new to collecting autographs and I’m having some difficulty figuring some things out. Most of the people I want to send to are in the United States, which is a problem for me because I live in Canada [ca]. I can buy Global forever stamps online for my SASE’s but there is a huge markup on them which adds almost $5 CAD to the cost of each autograph request. I was wondering if there are any websites that some of my fellow Canadians use to get stamps or if people have had much success including money instead of a stamp. And if money does work should I include American dollars or is Canadian dollars fine? Thanks in advance everyone :)