Looking for a bit of guidance on how to handle this scenario.

A part time member of staff who is a student and studies in location A in the UK. The place of work location B is currently a Tier 3 lockdown area. They spend their week studying in Location A, then stay with family in Location B on the weekend so they can attend their weekend part time shifts. 

i think that currently the guidance is try to avoid leaving the tier 3, for anything other than employment or education purposes. Also to avoid over night stays in other areas of the UK if they are from a tier 3.

I dont think theres anything wrong with the person attending both work and university as it is just guidance for now. The only issue would be if the student acomodation was to isolate, which has happened in certain areas. But obviously they would have to isolate regardless if its required.

I thought universities had issued their own student guidance about avoiding yo-yo travel between halls and home

Spending a weekend working in an area of Very High Risk and staying with family to return to residence / lectures with others whilst legally permitted (travel for work and education) is morally questionable.

The accommodation is more likely to end up isolating with this individuals current practices. 

I agree I dont think its work related - and yes its only guidance, but students have been advised not to travel home during term time - basicaly pick a lovcation and stick to it.

Also the Public Health Guidance states People should avoid staying overnight in another part of the UK if they are resident in a ‘Very High’ area, or avoid staying overnight in a ‘Very High’ area if they are resident elsewhere.

If this guidance becomes law at some point (as it has in Wales) then it may be problamatic.

At the moment i would say its not in the spirit of the public health measures.