The RN did not intend their BC's to operate in any really way detached from the main body of the Grand Fleet.

They in essence filled two general purposes, one better than the other. One was to provide staying power to their screen and scout forces. They could press home a reminiscence with destroyers and light cruisers to ascertain accurate information on the makeup, location, course, and speed of the enemy fleet, then maintain contact while the Battle line of the Grand Fleet moved in to engage. That is where the speed/armor/gun tradeoff works for them, they are able to fight and not fear any German scouts or escorts, and by the time they engage any of either their German peers or the German BB's then their mission is a success and that is valuable information as they have located major enemy units.

The second function was to act in essence as the "Fast Wing" or flying column of the battle line in that they could both redoply and reach the scene of decision quickly over large tracts of sea to add their considerable firepower. This was rather secondary in prewar theory and initial doctrine, but come the real shooting the whole idea of "if it weighs like a battleship, and has guns like a battleship, it can be used like a battleship" starts to creep in so the BC's start being expected to fight at the least the German BC's so as to take them out of any battle and keep them from doing the same end around on the British. This role though was later given basically to the Super Dreadnoughts of high speed which came on line as the war progressed, a squadron of which were under Beatty's command at Jutland and which he damn near criminally misused. The concept of this would resurface just before WW2 in the "Fast Battleship" which peaked with the Iowa Class in the USN, except this time they really did have the staying power to be ships of the line but extra fast.

As for how they were used I will speak to 3 general situations.

The first is the early war Med. # British BC's were attached to the fleet out of Malta to make sure the German BC the Goeben couldnt interfere with the French bring the Foreign Legion and African troops to Europe, and to try to prevent any potential Austrian outbreak from the Adriatic. In both they were successful, but the Goeben and her escort escaped to Turkey where later they were almost singlehandedly responsible for bringing Turkey into the war on the Central Power's side after the ship went off and shelled Russian harbors.

Then weeks later 2 BC's were dispatched as an emergency force to the South Atlantic and the Falklands after von SPee had eliminated a hodgepodge RN squadron at Coronel on the Pacific Coast of South America. Spee unfortunate for him though took his ships (centered on two armored cruisers) in to Port Stanley just a few days after the RN reinforcements arrived and the BC's easily eliminated his East Asia Squadron in a running battle of several hours.

And finally you have the main British Battlecruiser Squadron under David Beatty attached to the Grand Fleet stationed on the coat of Scotland. The squadron operated as a unit, growing from 4 ships to almost a dozen and being divided into several squadrons again and designated its own fleet subordinate to the Grand Fleet.

Their entire role was to be a the fast reaction force, to get to the scene of a German raid or foray before the Grand Fleet, fix the location of the enemy or at least make contact and break through their screen, or pin major enemy units in place to be destroyed later. It honestly only worked a handful of times, Jutland being sort of one, and on other occasions left them perilously far from support and close to potential destruction themselves, but at the same time on several German raids also came close to meeting isolated German units and potentially picking them off too. Of note they also on several occasions assisted the light forces and in particular the subs and destroyers under the Harwich Flotilla. One battle I will point out was the Dogger Bank where the two opposing BC Squadrons engaged in an hours long chase with the RN sinking the German Quasi battlecruiser Blucher, while the rest of the squadron got away with varying levels of damage, due to a breakdown in communication after Beatty's flagship Lion suffered major damage and had to be towed back to port. It was at this battle that the Germans really began to appreciate the danger poor safety practices could pose in their magazines and turrets, and how much more ruggedly constructed their ships were along with their excellent gunnery which left a strong impression on the British.

In all circumstances the goal was to try to have BC's operating with at least a flotilla of a dozen destroyers and a few light cruisers to provide screens for submarines, torpedo surface craft attacks, and extend range of contact, but the Grand Fleet was more vital and there were never enough small craft to go around.

And excellent introductory read is Massie's Castles of Steel, probably the premier modern one volume on WW1 at sea.

Britain maintained an effective blockade of the German coast and did not need raiders.

The battlecruiser squadron was the heavy-hitting element of the scouting force for the main fleet and as such fulfilled a role analogous to that played by the advance guard in land warfare: providing information and avoiding ambushes. Being fast vessels, they could enable a decision to engage or disengage to be made in reasonable safety because even if they found themselves isolated and outnumbered they could hope to outrun the enemy. They were still valuable capital vessels though, and so would have their own screens of cruisers and, circumstances permitting, destroyers. These smaller vessels would provide protection against submarines (by forcing them underwater where they had limited mobility) as well as scouting for them just as they themselves scouted for the main fleet.