Sorry I didn't respond sooner; I had to work late last night. Just to add to what others have said, I found this from what appears to be an official historical monograph from 1957,
The Defence of the United Kingdom, digitized on
Gawdzilla's website:
. . . In the autumn [of 1938] the German attitude became so threatening that the British Government ordered an emergency deployment of a great part of the home defences.
The deployment was not a full-dress rehearsal for mobilisation. Neither a state of hostilities nor the 'precautionary period' for which the various departments of State had drawn up plans was deemed to have begun. In some respects conditions were less favourable for rapid moves of units than they might have been if emergency measures had been applied more widely. Nevertheless the experience provided a convincing demonstration of unreadiness for war. In Fighter Command twenty-nine fighter squadrons were reckoned mobilisable, but only five of them had modern aircraft. Even those five were incapable of fighting at high altitudes, for their guns had not yet been modified to work above 15,000 feet. There were also five squadrons of Gladiators, old-fashioned in appearance and no match for modern fighters, but capable of engaging bombers. The rest of the fighter squadrons had obsolete or obsolescent aircraft. There were no stored reserves of fighter aircraft; immediate reserves with squadrons and in workshops amounted to about two-fifths of first-line strength. The radar chain gave partial cover only between the Wash and Dungeness, communications were incomplete, and the whole command was dependent on radio equipment much inferior to that which replaced it in 1939 and 1940. The London balloon-barrage was only about one-third ready--142 balloons were deployed towards an establishment of 450--and its deployment raised many problems, not all of which had been foreseen. The state of the anti-aircraft and searchlight formations was still worse. Nearly 50,000 Territorials joined the air defence and coast defence formations when summoned, but only about one-third of the anti-aircraft guns and lights proposed by the Reorientation Committee in 1937 were available. Some of them were not in working order or were accompanied by unsuitable ammunition or equipment. The majority of the guns were of the obsolescent 3-inch pattern, some fifty 3-7-inch and no 4-5-inch pieces being ready. Arrangements for billeting and the issue of stores left much to be desired. Measures of Civil Defence were hampered, according to the Air Raid Precautions Department of the Home Office, by undue regard for secrecy.[ETA: citations and note omitted]
Henri will doubtless seize on the above as evidence that Britain could have been bombed into submission in a week, while conveniently ignoring the facts that a) terror bombing by itself has never led to the capitulation of any nation, and b) the Luftwaffe had a lot of very serious deficiencies of its own at this time.
Further, many of these deficiencies were, or could have been, quickly remedied, especially with the impetus of war. For example, the high-altitude gun problem was solved by the expedient of covering the gun ports with fabric patches, and dedicated landlines were being installed in order to communicate radar data.