If you're talking about thousands of British troops fanning out across the countryside, this probably better suited for /r/historicalwhatif.

That said, the British war effort involved much more than columns of redcoats marching out of central barracks. The British had a very large and active network of spies throughout the colonies.

They fought alongside a number of allied Indian nations, arming and supplying others. These allied nations often staged guerrilla-style raids rather than fight pitched battles.

Loyalists rallied to the British cause; not only did they fight under British command, they staged small raids and attacks too numerous to count in every theater of the war.

In 1775, Britain's Lord Dunmore offered freedom to any slave who deserted a Patriot master to fight for Britain. Thousands took this opportunity. While most of these refugees joined organized units, many faced terrible hardships (and some number of them had to fight) to escape to the British lines.

It's also worth noting that guerrilla warfare is especially difficult if you do not live and reside in the country you are fighting in. You cannot melt back into the civilian population if you do not belong to it. You can't rely on the support of the locals to hide, aid, abet you while undermining or sabotaging the enemy if you do not have it.

Certainly all the things mentioned by other posters fit the definition of irregular warfare and were in many cases, some of the most successful tactics that the British employed. Namely their raids against slave holders along the Southern coast and their work with the Indians.

It is also ironic that though George Washington is now lauded for his guerrilla tactics (and success), because if he could have Washington almost certainly would have fought more traditional battles. He just did not have the troops or the resources.

I'm sorry, but as /u/prufrock451 pointed out, we ask that these questions remain in /r/historicalwhatif. Thank you!