You need to look at your budget with just you in the house. Being able to retire should be a good incentive to get better at managing your money.
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You'll pay less council tax, less food if you've been buying all the food now, utilities might be a bit less, but maybe not significantly so. Can you downgrade the broadband and pay TV if you 'need' less than young adults like to have?
You could have a look at the Moneysaving expert money makeover, to get a really good luck at your outgoings, because if you trim down all your fixed costs a little, and watch your spending if you're currently spending a lot it could make it that you can afford to retire.
Also remember that the tax allowance and lack of NI on pension payments will mean that your income won't go down by half, but maybe to 60% or so of what you take home now.
Try putting your salary and pension income into an online calculator to work out exactly what it will be - it will be a different percentage if you are going from £20k to £10k pa vs £80k to £40k pa.
How old are you? I'm guessing that you're in your early 60s and are entitled to something like a full civil service pension, but not state pension yet - remember that when you reach state retirement age (65 or so now?) you'll get that, which is another £8k ish pa.
Or if you really can't afford to retire, can you cut your hours down to 2 or 3 days a week?