Speaking from the team hotel, May told the club website that things had moved very quickly.
"It's all happened really quickly and come as a bit of a shock. When I didn't make the touring squad, I was told that I'd be on standby but you don't actually expect to get the call.
"It's tough on Mike Brown and George Lowe. Getting injured is tough at any time and I know they'll be devastated at being forced out of the tour. They're good guys and great players and they'll bounce back."
Gloucester's preparations for 2012-13 will begin later this week as the first batch of players report back for meetings ahead of training starting in earnest next week and May admitted he'd been relaxing ahead of the hard work to come.
"I'd been recharging my batteries, getting away from rugby a little bit and just preparing myself to report back for preseason training with Gloucester. Then I got the telephone call and now I'm in South Africa.
"It's all a bit surreal. I watched last week's Test on the television and now I'll actually be at the stadium in Johannesburg watching the team take on South Africa.
"I only landed this morning and am actually feeling quite good. The team are obviously focussed on preparing for the Test so I've just been relaxing and doing a bit of a spin session on the bike to get the flight out of my legs.
"I had a chat with Stuart Lancaster on the phone last night and he told me that I'd probably see some action in the midweek game. I did see Mike Catt when I arrived and he welcomed me and said that he'd have a good chat with me after the Test.
"So, I guess I'll feel a bit more involved in a few hours time. Obviously Adam (Brett, the Gloucester Rugby physio) is out here, so there's one familiar face and I know a few of the lads from the Saxons.
2011-12 was very much a breakthrough season for the Swindon born 22 year. His previous highest number of starts was nine in 2010-11 but this was dwarfed by his 22 starts last season.
His progress was reflected by a host of award wins including LV= Breakthrough Player, Aviva Premiership Player of the Month and Aviva Premiership Try of the Season.
"It's been an amazing season really. Playing for Gloucester regularly, then being involved with the Saxons and now this.
"It doesn't take away the disappointment of how the season finished for Gloucester but, what I'll try and do, is make the most of this experience and become a better player for it."