We will try to get the account opened and funded before the end of the year, but I fear we may have left it too late
The reality is that it's not too late. It's just that you've left it late to start researching how to do it, and do it right. You're also limiting yourself to just one provider by choosing Vanguard.
On these contracts, I'm not a fan of not having a clear trail of the source account (in both donors names) of the money, where it ends up, and its intended purpose. The donor/s may not be around to help the recipient with the paper trail.
You could, in reality, request the paperwork today, complete and submit it ( including AML documents) , be provided with EFT details of the life assurance company to do a transfer of €6,000 to and start a direct debit for €500pm from 01/01/2025. The €6,000 would be invested from date of receipt by the life office. Job done, and policy documents issued to you in next 7/10 working days.
But, that's the execution only model where you don't need advice on knowing what provider to run with, the exact product to request the information on and the fund/s you want to invest in.