The BBC took most of the Eastenders clips down, sadly.
I watched most of the story, although I didn't see the time when they got together.
Tony and Simon were a very ordinary couple. They didn't have gorgeous faces or perfect bodies, or glamorous lives. They spent most of their time dealing with their families. Simon's sister Tiffany was always battling with her bully husband Grant, and Simon's parents were both weak, selfish people. Tony's father was an abusive homophobe, his sister was an idiot who at one point used religion to reject him, and his mother was a money-hungry shrew who married Simon's father.
Many of their problems stemmed from Simon's insecurity over Tony's bisexuality, which was justified when Tony had several affairs with women. First a one-night stand with a singer, and then a longer relationship, with a very annoying reporter named Polly who had fried hair. Simon was very needy. He'd just gotten out of an abusive relationship before he'd moved to Walford.
They broke up for a year or so, then, when Tiffany died, Simon went crazy and tried to kidnap his baby niece. He was also caught up in a fire and badly burned. When he recovered, he went back to Walford. Tony was going traveling and asked Simon to join him. At first Simon said no, but then he changed his mind. They shared a brief kiss (one of the few they had on the show) and left together, never to return.
They were a solid couple. I really liked Simon, I was sorry to see him leave. I especially liked his slightly bitchy friendship with Bianca.