Terrified mum seeking info

Hi everyone,

I hope you can help me seen as DWP have been incredibly unhelpful.

My son has a place at University starting next month. It is a full time course (he got in through clearing after trying his very best at his A'levels). In truth, I never expected him to go to Uni but I have always encouraged him to push himself outside of him comfort zone.

Well my chickens have come home to roost!

J currently claims U/C (LCWRA) and also has high rate PIP for care and mobility.

His student maintenance loan is based on mine and my husbands salary and has been calculated as £4915 a year.

I understand that U/C will be reduced pound for pound but I can't figure out it that happens automatically or if we need to tell them? If the U/C is reduced my his maintenance loan amount of £4915 does this happen across the 7 month term time meaning he will still received some U/C monthly, his maintenance loan is 3 payments and will he still get his PIP?

Sorry for so many questions. I feel sick enough that he is going but how can I put plans in place for him if the information from DWP is so poor it is practically non existent?