Easy-peasy. Bitter is one of the simplest ales to brew, and is quite satisfying. You don't really need a kit; just take a recipe to your LHBS and get the stuff!
Here's a good recipe, from right here on HBT.
My recipe follows:
Sebastian's Special Ale
A ProMash Recipe Report
BJCP Style and Style Guidelines
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08-A English Pale Ale, Standard/Ordinary Bitter
Min OG: 1.032 Max OG: 1.040
Min IBU: 25 Max IBU: 35
Min Clr: 4 Max Clr: 14 Color in SRM, Lovibond
Recipe Specifics
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Batch Size (Gal): 5.50 Wort Size (Gal): 3.00
Total Extract (Lbs): 6.50
Anticipated OG: 1.039 Plato: 9.85
Anticipated SRM: 6.9
Anticipated IBU: 21.5
Wort Boil Time: 60 Minutes
Grain/Extract/Sugar
% Amount Name Origin Potential SRM
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92.3 6.00 lbs. Briess LME- Gold America 1.035 4
7.7 0.50 lbs. Crystal 55L Great Britain 1.034 55
Hops
Amount Name Form Alpha IBU Boil Time
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1.00 oz. Goldings Pellet 4.00 16.1 60 min.
1.00 oz. Goldings Pellet 4.00 0.0 0 min.
Yeast
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Danstar Nottingham Ale