It depends on your age.
And you're talking about TWO state pensions = £25K.
If you are in your 90s, don't drive, don't go on holidays, don't buy many clothes etc, then you could JUST about manage.
But AS A SINGLE PERSON out of the £12K state pension, £3K could go on council tax, £1.5K on utilities. £1K on water rates, then there is house insurance, car running costs, food, clothes, gifts for family, etc etc.
I think you're confusing things when you talk about a £300,000K pension pot. That equates to a monthly income, although some people take it as a lump sum.
For example, a pension pot of £1.2million might give an annual pension of £40-60K, with or without taking a lump sum up to £250K.
If as a couple you will have 2 state pensions = £25K a year you could survive but it would be tight.
The issue will be if you are widowed and have only your own pensions.