His symptoms are normal based on the fact that they did not do a follow up right after you called them and told them he was having terrible headaches.
They should have brought him back in as soon as you called and told him the symptoms. About the only fix for that problems is a blood patch to stop the leaking of csf. Surprisingly, it seems that the uk is a place that you do not want to have an lp done. There are many folks here that have had terrible experiences with the procedure over in europe and mostly in the uk.
I have had several lp/myleograms and have never exprienced any complications with leaking post procedure.
They were correct to tell him to drink lots of fluids and gatorade would probably have been the best to drink.
Hopefully he is doing better now and to my knowledge he shouldn't have any further complications as long as he did not pick up an infection at the hospital.
Good luck,
brian