What it says in the title.
IF Nazi Germany concentrates its military efforts on the UK and Empire, how quickly can it force the UK to seek a peace deal?
The following qualifications apply
1) The US supports the UK as OTL, with Lend-Lease and other aid.
2) There is no Operation Barbarossa but the Germans need to maintain a large army and air force to deter Soviet attacks.
(Say 100 Divisions and 1,500-2,000 aircraft initially, and that force may need to grow as the Red Army grows stronger)
3) Assume no Japanese attack on the Southern Resource Area OR that such intensifies US support for GB even without a DOW by it on Germany and Japan.
Frankly, the main problem for Germany is, that it really can't effectively threaten that much of the British empire. Most of Africa outside the North of it, and most of Asia aside from Middle East (and even that one is highly difficult), are completely unreachable, for Germany, and without Japanese invasion, they can continue fully supporting GB.
So, the 2 main places that are in reach of Germny are the UK itself and North Africa. The implausibility of the Seelöve invasion actually taking Britain out of the war has been dealt with numerous times here, so the German forces are either going to sit in French cafees untill mid-1942, or be lost in a suicidal invasion. With the leand-lease still going on, the British are certainly not going to loose the air-war, which will probably continue on.
Then there is the North Africa campaign, in which the Wehrmacht might well use much more resources then in OTL. However, would it really matter? At their greatest reach at El Alamein, the Axis forces had their logistics extremely overstretched, and further advance, especially with more millitary units present, would be highly difficult. Then they would actually have to cross the Nile river, and later on Suez itself, both of which would be well defendable. So perhaps we might see a further advance by Axis in Egypt, though one hampered by supply and harsh British-Commonwealth deffense. And even if the Germans and Italians by some lucky roll manage to get beyond the Suez, what then? The British can still put up further deffensives in Palestine and Egypt. While the loss of Suez would be a blow for the British, loosing the Eastern Medditarean will not loose them the war.
So, no I don't think its possible to force a peace deal, even with these changes. The Axis can cause more damage, that is certainly possible, but not ones that would force the British to give up the fighting. Oh, and in this scenario, I would expect the USSR to join the war by July 42. Their army would have finished its modernizations, and with so much of the Axis forces concentrated in France and North Africa, I would expect Stalin to fell secure enough to launch a full invasion of Europe, sometime after the 1942 Rasputica rains are finished.