Hello
First off SBG has moved into the new WarBands ruleset where 1 hero leads 0-12 troops. You should check out a local hobbyshop for the new books (probably the relm of men or something along those lines that has Rohan in it). It has some exciting new rules for Rohan units, you should take a look
As per your army, you really are not hero heavy enough to warrent the royal banner for Gamling. If you MUST have him, I would take him without the banner and bring a few more troops. As you have erky, and some spare points, it also wouldn't hurt to use the new Riders of the Westfold upgrade from the new Warbands books. I would also drop your capitain and bring more troops as well (as with theoden, erky, and gamling you have at least 36 troops to buy before you need to consider another hero) And if you are going to grab another hero, at least make it Grimbold who can upgrade your Warriors of Rohan. Right now, your biggest problem is you are too hero heavy and don't have enough foot soldiers. If you were to face Isengard right now, you would be outnumbered by superior soldiers and in serious trouble. Theme or no theme, there is no honor in suicide.
Why don't you think about what I said and write up another list and maybe you won't think it's so rubbish anymore