(The CAA used to qualify this as being 1000 feet above the runway).
Still do
8 Approach Ban -All Aircraft
8.1 The requirements for the commencement and continuation of an approach are defined in Articles 38, 39 and 40 of the Air Navigation Order 2000.
8.2 An aircraft may commence an instrument approach regardless of the reported RVR/Visibility but the approach shall not becontinued below 1000 ft above the aerodrome if the relevant RVR/Visibility for that runway is at the time less than the specified minimum for landing.
8.3 Where RVR is not available, RVR values may be derived by converting the reported visibility in accordance with paragraph 7.
8.4 If, after passing 1000 ft in accordance with paragraph 8.2, the reported RVR/Visibility falls below the applicable minimum, the approach may be continued to DA/H or MDA/H.
8.5 The approach may be continued below DA/H or MDA/H and the landing may be completed provided that the required visualreference is established at the DA/H or MDA/H and is maintained.
Aip AD 1-1-17
If you are passed to tower after passing 1000 feet then something has seriously gone wrong. The tower will asking radar for you long before this point. You wiil be given the RVR before you reach a 1000 feet agl, indeed usually on first contact with the tower. There is no excuse of saying that we had passed the decision point which is for these conditions 200 feet or so.