Yes that Farnborough notam looks dreadful. The RIAT one (run by Brize) is similar.
But the smart thing to do there is to get onto ais.org.uk and print off the AIC referred to. It doesn't take long to find it - assuming the pilot is internet-savvy which many aren't (especially the "older" sort). There is a nice picture in there. But I am certain the majority of UK PPL-level pilots have never heard of ais.org,uk and won't hear anything about it either 10 years from now.
The notam should contain a short URL to the document.
Someone from NATS has kindly provided the information that the ICAO requirement is for the data to kept 30 days. Any request for the info to be pulled would normally be made within that period. In practice it's kept for 90 days.
Nowhere near long enough for what the French have been known to get up to
Clearly the solution, for anyone flying in France, is to print out the notam listing and keep it for 1 year (or save it in a file). That's what I do.