So I did a little bit of google research:
In order to break a Guinness World record you first must fill out an application for the record you want to break. When they accept your application they then send you a packet about the record you are trying to break and info about it as well as an evidence packet explaining what to do when you break your record. Once you successfully attempt the record thing you're trying to break you send the proof over to their HQ in London. You cannot send evidence without having submitted an application.
This is what they say about having a Guinness Record person there at the time of the attempt: You are not required to have an Adjudicator present when you attempt a record - but if you do not, you must carefully document and record your attempt so our team of Adjudicators can assess the evidence you send to us and verify whether your attempt has been successful.
Should you wish to invite a Guinness World Records Adjudicator, and get immediate confirmation of the outcome of your attempt, you can purchase on-site verification from our range of Adjudication Services.
So there you have it for anyone trying to break this record haha