LB:
EVERYTHING you get now (inc the SERPS element of your pension) will increase by 10.1%. That's confirmed in the booklet that comes with the letter, which I've scanned here:
https://i.postimg.cc/KcgPbnDf/Pension.jpg
So, to work out how much EXTRA you'll get, multiply your current payment by 0.101.
Alternatively, to get the new TOTAL amount, multiply by 1.101.