Est color: 17L
ABV: ~6
Ibu: 39
Steeping Grains:
1Ibs ESB pale malt- Gambrinus
5.0 oz caramel/crystal malt - 120L
3.0oz chocolate malt
Fermentable's:
1Ibs Amber DME
6ibs. Gold LME
1ibs. dextrose
Hop additions:
1oz Warrior 60min
.75oz Willamette
You're aiming for that british pale (ale) malt character that is found in those pale malts that are kilned a little darker. Since the bulk of your fermentables will come from extracts then you would serve yourself best by looking for extracts known to give you that British pale malt character. I don't know exactly what's out there in terms of options but anything labeled as maris otter extract or british pale extract would be an ideal place to start; or, just buying an pale extract from a british maker (munton and fison) as opposed to USA maker (Briess). This will be key to getting down the correct base malt characters.
Next, a couple steeped british crystal additions should land you right about where you want to be in terms of overall malt character. Half a pound of medium crystal (40-50Lish) and quarter pound of dark (~120L) is a reasonable place to start for 5 gallons.
If you're dying to fine-tune the color then 0.5-1.5 oz of a roasted malt will get you there, but is probably unnecessary for a first batch.
Dextrose if you want but I prefer without.
1968 yeast is an excellent choice for this beer.
British hops would be best but a little warrior at 60 to get the IBUs up isn't terrible. I think you can get a softer bitterness by using moderate-alpha hops (challenger, fuggles, etc) and finishing with others like willamette or east kent golding. Warrior is known to be a neutral bittering hop so I don't see anything terribly wrong with it - just not British
.
Ferment at 67-68F (beer temp) for 7-10 days and you're set (check FG of course).
If your local homebrew shop (lhbs) has a website then post it and we might be able to help you dial in some specific ingredients. You could also brew exactly what you posted in your original post and it will make a good beer - I just don't know if I would think of it as an ESB.
Gambrinus ESB = Extra Special British (gambrinus is canadian)
ESB beer style = Extra Special Bitter