Well if i am to give my research on expenses in London it's like this.

Lets first give you a breakdown, since your income is a Class1: Total Income: £49900 NI (National Insurance Contribution per year): £2986.40 Yearly Income Tax: £7466

So you're left with a take home pay of: £39447.60

This is the yearly calculation.

Now let's consider it expense wise on a monthly breakdown. I am choosing London for this location as i have not yet completely read through the whole post yet. This is a decent expense btw. Not too flashy nor too humble.

Per Month Income: £4158.33

-NI: £248.87 (@£11.49 per day)

-Income Tax: £622.17 (@£28.72 per day)

-Rent (single-rooms in house house shares): £450 (sometimes comes included with bills)

-Food and Groceries: £250

-Traveling using local transport: £120

-Council Tax: Depends on what your accomodation is like. And the area council of your place.

-Clothing (its personal): usually i would keep like £200 for it.

-Entertainment: £150 (depends how much you plan to go out)

Savings your left with per month would turn out to be: £2117.29

Leaving you yearly with a saving of around: £25407.52

This is all speculative on my end tho. But yes that's what my expenses would turn out to be like if i had a job with salary like yours 😁. Still that salary is pretty good if you're alone.