I'm just hoping we have some clarity before 29th March as that's about my deadline.
Aren't we all
.
Article here
https://www.vanguardinvestor.co.uk/articles/latest-thoughts/how-it-works/what-is-pound-cost-averaging agrees with Shark but does mention 'insurance against regret'
'Nobody likes the idea of investing a significant sum of money, only to see the market drop immediately afterwards. For some investors, this fear of regret leaves them paralysed. They decide to wait until they feel more confident about the market, but this time may never come. For these investors, pound-cost averaging may be a way to overcome their paralysis and at least get some money into the market.'
So if you have the option of investment but are putting it off, one route round this may be invest some now and then rest later. The averages may say that you are more likely to do better by investing all now (though there's also a lesser but still significant risk that you might be worse off) but hedging by splitting investment may make it easier to invest and may even actually have some risk mitigation justification given the high degree of uncertainty around end of March.
Actually facing similar situation with some inheritance money of my daughters which she (with my advice) needs to decide what to do with.