I have read that it's important to check the bid ask spread and the ETF volume to determine its liquidity.
As a case of study, let's take the Vanguard S&P 500 ETF in the UK (VUSA).
I have searched it in morningstar: https://www.morningstar.co.uk/uk/etf/snapshot/snapshot.aspx?id=0P0000WAHG
and I have read the ETF's prospectus
but I have found nothing about the above mentioned parameters.
Moreover, I don't even know what would be good quantities for them (what concerns me is being able to sell the ETF as close to its NAV as possible).
Where can I find these parameters, and how can I judge them (what would be good quantities for the above concern)?