Well, it's lucky there's a toilet to be sick on. Martin will spend... a good while just being sick and miserable and self-pitying. He'll probably even have himself a little cry as this cursed flesh prison of his rebels. He misses the apocalypse. He didn't have to eat or drink. Can he go back to that, please?

He knows he's running out of options to get out of here and he's still pretty darn certain that help isn't coming for him. If he can manage to not be making use of the gross toilet for a little while during the day, he'll use his faux-leather jacket to wrap around the bar that looks the rustiest, sit down, plant his feet on the bars and use his legs to pull on it. He's a pretty big guy who spent god only knows how long walking from Scotland to London through the fearpocalypse. He has more faith in his legs than his arms to actually accomplish anything here if it's going to be any sort of possible.

EDIT: Because Squalo offered some additional suggestions... Martin will also try checking under the mattress to see if there's some trap door or hole that he's missed there. He'll also try to just physically push the door up in spite of the deadbolts. He won't spend very long on that if it's clear the locks are for more than just show.