If you want to play an English game, play Super Robot Taisen: Original Generations 1 and 2.(THE OG series don't contain any Gundams and such however, because as the name implies its a sort of anniversary game which brings all the original players and units spanning all the different games under one game, its quite awesome actually)
After you have played those and learnt how controls and the game systems work, you can play 90% of the other games out there because of the similarity of spells and menus and such.
Its sad because SRT:OG1+2 are the only games out there in English.
For something easy and accessible you can try SRW-W on the DS, if you want something with jap voices and better graphics, play SRW Alpha 3 on the PS2.