Welcome to the forum Jacqui. What do you mean by 'the engine light' and have you looked in your owner's manual to identify it correctly? There are lots of lights on the dashboard at startup and not all of them mean what you think they might.
If it is the diesel particle filter warning light staying on then the cause of this needs to be resolved as a matter of urgency, to avoid engine damage. If the filter is significantly blocked (and this depends on driving style and quality of fuel) it has to be cleaned out by a specialist. You can try driving non-stop for about 25 miles in 4th gear at not less than 2200 rpm and at a constant speed to generate the heat necessary to clean the unit before spending too much money. If it is a DPF fault bear in mind that previous owner(s) might not have followed the simple rules to keep it in good condition. This seems to be a common problem with used Antaras - basic neglect.
2015 2.2 CDTi SENav 163ps manual 4x4 in Carbon Flash with 19\" alloy spare towing a Bailey Unicorn III Madrid @ 1500kg.