In terms of missing out of the dividend payment I don’t think we’ve got anything to be concerned about. The ETF price should be continually adjusted throughout the year to account for any accrued dividends that have not yet been paid until the ex-dividend date. It is explained at https://www.schwab.com/learn/story/understanding-etfs-and-dividends
More alarmingly I have just found the thread at Delisted fund (Amundi EPRE) - what to do to retreive asset value? which discusses the problems people had last year when other Amundi ETFs were delisted from the LSE.
Unless the situation is somehow materially different for this Amundi Prime Global ETF corporate action I think the only sensible thing is to sell before the middle of November. Ideally InvestEngine would do this automatically for their customers rather than waiting until after the event and leaving people stuck in limbo for weeks or months with an ETF that cannot be traded on their platform.