@Hooplahooping the suggestions from @ClematisBlue49 have many advantages, at least in the short term. They give you maximum flexibility while earning a bit of income in a tax-efficient and fee-efficient manner, you can pretty much avoid any meaningful risk of losing money provided you choose short duration gilts, and you could do this pretty much straight away in order to get your money working for you, while you start the process of deciding what to do with the money longer-term, whether to hire an advisor, etc.
If this is money that you would like to use many years into the future, then there are other considerations worth exploring in the coming 6-12 months, and you would probably want to either gain some financial literacy or consult an IFA, or perhaps both. A good IFA could learn about to your specific circumstances in a structured way, present you with a few different options taking those into account, and explain the pros and cons of different options in a simple and understandable way. It is not rocket science, and if any IFA proposes something that sounds complicated, requires locking up your money, or involves high fees then you need a different IFA. My personal view on what is "reasonable" for fees, even for "full service", is that the all-in cost including the IFA fee, the platform (custody) fee and the fund management fee should absolutely be below 2% per year, and I would really rather see below 1.5% and as close as possible to 1% all-in.
Some of those other considerations would include:
-as a PP asked, do you have any debts? you said you are mortgage-free but if you have a car loan or credit card debt it might be worth repaying that first, depending on the terms and conditions (a very low interest car loan might not be worth prepaying).
-do you already have a suitable emergency fund to cover unexpected expenses, and if so, where have you "parked" it and what sort of interest rate are you getting on it?
-might it be worth contributing to a pension plan (could be a SIPP or one attached to your employer)? This would lower your income tax immediately, but on the other hand there would then be restrictions and taxes due in the future when the money comes out in the future, so there are pros and cons to this option.
-do you have any sort of protection/insurance in place for bad things that can happen in life (eg unemployment, illness), for instance through your employer, and if not do you want to explore any of the options for that?
-are there any major purchases you might need to consider (eg car replacement) in the next few years?
-what other sources of income do you expect to have available in retirement?
-conversely, is there anything that costs a bit of money that would bring you genuinely meaningful experiences and genuine joy? Frugality is liberating in many ways, and on balance I think it is a good thing, that leads to less stress and more happiness, but there is such a thing as too much of a good thing.
-if there are no major cash needs in the next 5-7 years, and if the main purpose of the funds is for retirement, then when would you start to draw the money down? If it is quite soon then capital protection is paramount for at least part of the money, but if it is in 7-10 years or more then inflation starts to become the bigger risk. And if you want this money to be drawn down over a longer period of time, then inflation is again probably the bigger risk for every pound that will be withdrawn 10+ years into the future.
These are questions for you to think about with your partner and/or with an IFA. Except for the first one (about paying debts), they can be addressed after you have found a sensible short-term way to park your money, whether it is using the suggestions by @ClematisBlue49 or another way. It certainly does NOT belong in a current account with a single bank!