This guide was quite helpful to me:
Converting All Grain to Extract/partial mash
The fuggles smash recipe is pretty simple, take your amount of base grains and multiply by a factor of .75 if you're using LME or .6 if you're using DME.
8.25 lbs of British Pale malt extract (liquid)
6.6 lbs of dry extract of the same type.
Or you could do a partial mash with Maris Otter malt. For every pound of grain you mash, reduce the amount of extract accordingly. It's pretty easy to do with a grain bag and a small cooler or pot ala Deathbrewer's tutorial
Depending on how much you can boil with your setup, you may want to adjust the hops a bit or add extract later in the boil to keep the same hop profile of the original recipe. One of the calculators can help you with your adjustments.