Split it in 3 pots of 100k each:
Pot 1:
Used for my mortgage contributions. Almost covers my half. Let's say crudely this covers me for housing at a cost of £500/month for the next 16.5 years. (I may of course choose to pay this in one lump sum and let my husband pay his over time)
Pot 2:
Used as income support. Covers my bills at a rate of £500/month for the next 16.5 years.
Pot 3:
Straight into the pension, you guessed it, covering 16.5 years of contributions in one go.
I would make plans to leave my job (paying 52k) in the next twelve months, and save hard for a year of travelling, training, writing and enjoying myself.
I'd then return to work either on a PT basis or in a lower paid, less stressful job, with the aim that all I earn would top up my pension, savings and fun money. With the amounts above secured for 16.5 years, I'd only need a take-home income of 1300/month to keep my current lifestyle entirely intact.
Those who say these amounts are not life changing sums clearly have no imagination!