I'd reccommend you just start out with a normal cleric, and later on you can multiclass a bit if needed to boost your melee effectiveness, if you feel you need to. Of course, around the middle levels onward, clerics have access to the Divine Power spell, which temporarily changes their Base Attack Bonus to that of an equal-level fighter.
One possibility: start out as a 1st-level, lawful neutral, human cleric of Heironeus, with the Law and War domains, and choose to rebuke/command undead instead of turn/destroy them. This means you will cast spontaneous Inflict X Wounds spells instead of Cure X Wounds spells. Multiclass to monk at 2nd-level, then resume cleric advancement at 3rd-level onward. Then you could cast a spontaneous Inflict Light Wounds (or Moderate, Serious, or Critical, depending on your level) and punch an enemy in the same round, dealing 1d6+1d8+1 damage + your Strength modifier (with the 1d8+1 varying depending on your cleric level and what Inflict spell you cast; i.e. an Inflict Critical Wounds cast as a 7th-level cleric will, when making an unarmed strike in this way, deal 1d6+4d8+7 damage + your Strength modifier).
Of course, casting a spell within melee reach will require you to cast defensively to avoid attacks of opportunity, but with the Combat Casting feat, 5 ranks of Concentration, and 12 Constitution for instance, you would have a +10 on Concentration checks to cast defensively right at 2nd-level (+9 at 1st-level, but at 1st-level you wouldn't be a monk yet and wouldn't have as much incentive to use Inflict spells). Any time you face a foe with high AC, you can just slap them with Inflict spells as melee touch attacks, rather than using unarmed strikes to deliver the spell effect.
You could go the unarmored route or the well-armored route this way; at 1st-level you'd go with the best armor you could afford, after buying a longsword, wooden or silver holy symbol, and basic supplies. Once/if you multiclass into monk at 2nd-level, you might choose to sell your armor and thereby retain full use of your minor monkish abilities; your Wisdom modifier would be added to your AC, and you could focus on getting magic Bracers of Armor for a further AC boost, or you could get the party's sorcerer/wizard to cast Mage Armor on you at the start of each fight (Mage Armor isn't limited to personal use). Most likely though, it would be best to stick with using regular armor, and getting it magically enhanced later. Unless you have high Dexterity and Wisdom, and easy access to Dex/Wis/AC-boosting magic items. Even unarmored, the cleric spell Magic Vestment can grant your clothes an enhancement bonus to AC (which counts effectively as an armor bonus to AC, but without actually being from armor).
If you go the armored route, get full plate as soon as possible. In either case, don't bother with a shield; you'll need one hand fairly free in order to perform somatic spell components (clerics don't have arcane spell failure chances, but they still need a free hand for casting most spells). You'll wield your longsword two-handed, as you can remove a hand briefly for spellcasting no problem, and then resume your two-handed grip immediately afterward. Two-handed, you'll get 1.5x your Strength bonus to damage with the longsword, and your War domain and choice of Heironeus as a patron deity will give your Martial Weapon Proficiency (Longsword) and Weapon Focus (Longsword). Use spells like Divine Favor, Magic Weapon, Bull's Strength, Greater Magic Weapon, Divine Power, and such to improve your melee attack and damage bonuses. Also use spells like Shield of Faith, Bear's Endurance (just Endurance in 3.0 rules, dunno which you're using), and Magic Vestment to bolster your defenses.
If you get the chance to rebuke and command some undead, you can use them to assist you in combat. They can be commanded to flank with you in melee, or attempt grappling an opponent (thus causing that opponent to lose any Dex bonus to AC against you, while you proceed to hack away with the longsword), or use 'aid another' actions to improve your attack rolls or Armor Class. Or they can just be commanded to attack other enemies and keep them occupied while you handle other foes. Undead can also be sent forward to trigger any traps by walking right into them or the like, if you don't have a capable rogue to disarm traps more effectively. At middle and later levels, you can cast Animate Dead or Create Undead on enemy corpses if needed, to acquire undead minions.
