It is great that you can save that much, l assume other than mortgage you have no other debts?
You need savings for the unexpected ie, job loss but once you can realistically manage for 6 months in the unlikely incidence you both lost your jobs, then pay off the mortgage as fast as possible.
Unless you have a very long term fix always assume mortgages could go up hugely, people here have said how devastating some of those hikes were. Either pay it down or fix long term.
When l was in my 20s with my first flat in the South West in 1991, l was so worried about having a mortgage alone, and a tiny new business, that l worked 70 plus hours a week to pay it down, whilst most of my friends were buying their first cars on finance.
I was so frugal. Everything l owned was second hand from charity shops, my car was worth a couple of hundred pounds....
At that age you have youthful energy on your side!
By 30 l had enough equity to put a small deposit on a (admittedly grotty ) Zone 2 London flat which enabled me to take a job l wanted.
I shared it by turning the living room into a bedroom and renting it out, and carried on paying down the mortgage....still lived frugally,
These were the best decisions l have made in my life, as despite job losses, sever accident injury, and a business almost failing l have always managed to have a secure and affordable home.
Keep up your discipline now, earn any extra you can and don't spend it!
The last thing is ...remember it is 10 x harder to achieve these things as you get older.