No. Whilst it is often a bit hard to prove a negative, in this case it is quite clear that there were no German forces on the ground in England. Operation Sea Lion - the planned invasion of Britain - was designed to take place after air superiority had been achieved by the Germans, something which was never achieved. Sea Lion itself was really quite a half-baked plan, with little hope of success according to military historians and military officers who have studied it, and in any case it was postponed indefinitely in September 1940. German forces never invaded Britain.

There were German spies in England, of course, many of which were flipped into becoming double-agents. German forces also occupied the channel islands of Jersey and Guernsey, which dependencies of the British Crown, starting in 1940. That was the closest they ever came to occupying Britain, and it's not that close since Guernsey and Jersey are actually much closer to France (they are pretty close to Normandy) than they are to England. Other than that the closest thing I can imagine to "German forces on the ground" in England would be Luftwaffe pilots who ended up on English soil via crash landings during the Battle of Britain.

Source: "A British Plan to Invade England, 1941" by John P. Campbell discusses the feasibility of Sea Lion as well as how the British responded to intelligence of the plan.