"Hopefully I will be back".
"We're going to need energy for sure at this stage of the season - that's going to be as critical as anything - and then [decide] what's the best tactical approach to the game", he said.
Kyle Walker's sending off for two bookable offences also frustrated the Three Lions boss, who will now be without the suspended right-back in Copenhagen.
Southgate underlined that lack of match fitness when the topic of England's blunt attack was broached, although even he seemed surprised at the drop in sharpness during the game.More news: Serena through to US Open last 16 after battle with Stephens
"We conceded a penalty, we got away with it and we leave with a win that is really important".
"To get sent off for your country is never a nice moment especially after being out of the team for so long and being on 49 caps", Walker said, having put himself forward to speak to Sky Sports after the match.
England, who had earlier been reduced to 10 men after Kyle Walker was also sent off for second yellow card, had to survive that last-gasp scare when Iceland were awarded a penalty for Joe Gomez's foul but Birkir Bjarnason was wildly off target.
Southgate did not cut a sympathetic tone when discussing the 30-year-old, and admitted that he was not impressed with Walker's actions as it came as the first red card of his reign as England manager.More news: Multiple boats sink in Texas lake at pro-Trump water parade
"We knew this would be a very tough game given all the circumstances that have surrounded it for both teams and we have to move on now and assess who can go again on Tuesday". "I'm an experienced player and I should know I'm on a yellow card, and to make a rash challenge like that, it's not acceptable from me".
"We have talked a lot over the years about discipline and the amount of time we have gone out in tournaments when that has been critical - it is not what we want to see again".
With England's players severely short of match sharpness for this match, failing to beat Iceland wouldn't have come close on the shock levels of four years ago but the visitors were still heavily favored to win in an empty stadium in Reykjavik.
"The goal that is disallowed had a big bearing on the flow of the game", added Southgate.More news: Bangladesh: At least 18 dead following explosion at mosque in Narayanganj
Southgate described England's performance as a "real mixed bag". "A bit flat though because it feels we got away with it".