As ever, the mixed messaging is awful - as if it wasn't written in English:
"If you are in Tier 4, you should not be travelling abroad unless it is permitted. In addition, you should consider the public health advice in the country you are visiting."
Why the 'In addition'? Surely it should be :
"If you are in Tier 4, you should not be travelling abroad unless it is permitted. If you are permitted to and must travel, you should consider the public health advice in the country you are visiting."