Really do do need discuss this with an independent financial advisor - i.e. not one likely to pressure you into financial arrangements likely to be disadvantageous to you.
I am neither an IFA nor a pension-fund manager. Nor am I a barrister. I am replying based on my knowledge and experiences of several employers and now receiving both State and Company Pensions. I do though have the advantage that we both live in the UK. Other countries may have very different pensions and tax systems and laws.
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That decade of lower-paid work will obviously affect your savings and pension. So will how much you are saving additionally to any occupational-pension scheme now; and you need also consider any future mortgage.
Whatever "all this" was, presumably the Police or DEA will have an occupational-pension plan, probably a Defined Contributions one and perhaps allowing you to pay Additional Voluntary Contributions. All these plus whatever income and other taxes on salary are due, would be, or should be, taken from your Gross Pay so you don't need worry about finding the cash after you've gone and spent it all.
So leaving such service after 35 years instead of 45, means you sacrifice 120 monthly contributions, creating a smaller pot to cover your retirement.
Then, if you find that lower-paid work, will it have its own pension scheme? Possibly not; but anyway the lower salary means lower contributions.
Your previous pension investment will still be there but grow only by whatever investment returns its administrators can bring it. It is locked until your retirement age under it, and you have stopped paying into it. So it will still accrue investment earnings, but on a smaller investment; and remember that these things are always calculated by percentages so the smaller the principal, the lower the interest and the lower its rate of rise.
You would need find a private pension scheme. Van-driving or unskilled factory work may be too lowly paid to let you pay much into that private scheme especially if you are still paying a mortgage or are renting your home; and its nett (i.e. to you) investment return might not even cover inflation. It certainly won't be anything like your previous level.
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Also remember that pensions are taxed. Even the State Pension is, oddly, though on a PAYE basis so all we know is the nett pension. You can have company and private pensions as well, but the total income is taxable above a certain, quite modest level. I think the threshold is currently about £1200 / year. Although my total is not much above this Tax-Free Allowance, the income tax pretty well wipes out one of my Employee Pensions because it did not have very many years to run before I retired.
The whole field is very complicated, and in a very uncertain world. None of us can know how it will all work in over thirty years' time. If you succeed in holding well-paid work with a proper company-pension scheme for 35 years, stay with it. Certainly don't abandon it for lowly work for the last ten years of your working life!
And do your research. Even the best financial advisors can't predict anything decades hence but you should still seek their advice!
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Finally, you might consider why you'd want such a move in the first place; decades ahead. If you follow a Police or DEA career, or any other with comparable salaries and pensions, why would you want to consider leaving it so far ahead?
Some people in highly-responsible positions decline promotion if they feel they would not handle the higher post, or do not want to leave their present work, but stay with the organisation. You could instead consider staying there but requesting transfer to a less onerous post. It may mean a salary drop but you'd still be adding something to your accrued pension.
Others do retire from full careers in well-paid employment but take up shorter-hours, lowly-paid employment such as in supermarkets; but as pocket-money and a sense of purpose. Even this should not be considered without knowing your own finances, tax and pension implications at the time.
