You say the move "likely" won't happen now. You'd probably need to decided on this for definite. Re a buy to let, personally I wouldn't do that at the moment with house prices so inflated, there's a risk of a drop and unless you bought it in cash outright I'd feel it's a bit risky. Being a landlord is a hassle these days I think, too, in lots of ways. I decided against it.
The stock market is pretty up and down at the moment but if you don't need access to your money (or some of it) for 5-10 years then it might be worth putting some in a stocks and shares ISA. Something that's just done for you. I use Vanguard Lifestrategy funds for my ISA. It's hands off. You can put 20k per year into an ISA so you could put 20k in for this year and just see how it goes, as long as you don't think you'll need access to it. The rookie mistake is to watch it each month and panic when you see the value go down though and withdraw it all at a loss. It's there to be invested for the long term, and it will go up if you wait.
Re pension, you could look into topping it up a bit. That's very tax efficient. Obviously means the money is not accessible till at least 55 though so you'd need to think about that. You can pay in up to 100% of your annual earnings each year.
How old are your children? If they are likely to go to university are you aware that you will be expected to top up their maintenance loan yourselves, as parents, if your household income is less than £25k? For some uni accommodation even topping up would not cover it. I've had a shock at the cost of it all, and it comes about faster than you'd think when they are still primary age. So I'd definitely be putting some aside for that.
Interest rates are slowly increasing as I'm sure you know. A one year fixed savings account for some of it might guard against inflation a little bit. It'll lessen the impact any way. Other savings accounts might have a less competitive rate but may let you withdraw a few times before the end of the term. Personally I wouldn't fix for any more than a year at the moment as rates are likely to continue going up.
I know it sounds a bit odd saying this, but these days 50k isn't a HUGE amount of money. If you do a lot of research and learn loads yourself you could probably figure out how to put it to good use yourself with no need for a financial advisor who would take their cut. (and may not be interested in such a small sum anyway, unless you're already dealing with them for other things).
I think the world is a volatile place at the moment, personally, and I don't think ANY financial advisor could be 100% of giving great advice, other than "You need to minimise the impact of inflation".