‘Other’ work not HGV related

Hi,
I’ve heard that if you hold an HGV licence and this is your primary job you legally cannot do any other work like working in Tescos,pizza delivery,etc etc. So if you did do the odd paid job on the side technically you would be interrupting your rest pattern.
Cannot get a definitive answer from DVSA. Can anyone please confirm. Many Thanks

If you hold a vocational license and use it as your main employment then all other paid work must be declared as other work by a manual entry the next time you put you card in the Tachographs head.

If you drive under EU regs at any time in the fixed week then time spent doing any other job done cannot be rest for the regs

For confirmation that work other than driving should be recorded as other work in weeks that you drive in-scope of EU regulations scroll down to 4.3 Common Rules / Recording other work

ROG:
If you drive under EU regs at any time in the fixed week then time spent doing any other job done cannot be rest for the regs

My understanding has been that the time frame was not the “Fixed Week” but the period of time since the last Weekly Rest period - in effect his working week. As per 6(5) of 561.

Although 4.3 Common Rules is a bit double edged as it starts by making reference to “a week” and the only week that is defined in 561 is the Fixed Week. But then it goes on to say “since the last Weekly Rest period” or words to that effect.

So is the relevant recording period governed by the Fixed Week or is it since the last Weekly Rest period which could be totally different?