Luftwaffe grid reference info can be found at the excellent Gyges site:
www.gyges.dk/reporting_grids.htm
You want the LUMA Excel sheet here:
http://www.gyges.dk/LUMA.xls
and the guide here:
http://www.gyges.dk/LUMA%20Guide%20v2007%2005.pdf
Alternatively, you can grab the overall LW map here:
http://www.lesbutler.ip3.co.uk/jg26/gradnetz.htm
As for time, there is this classic post on the subject:
"This article was published in Bulletin Airwar 1939-1945 Nr. 99 page 26/27.
Time calculation 1940-1945. By Rob de Bruin/Great Bookham, England.
I have checked two sources; first my own Whitaker Almanac and I have contacted the Royal Observatory at Greenwich.
The situation is as follows:
1) In Great Britain (from now on called England) there is since 1916 summertime. In the winter they have GMT and in
the summer GMT+1.
2) Middle European Time (MET), that was the time in the Netherlands during the German occupation, was equal to GMT+1
and during the summer Middle European Time is equal to GMT+2.
3) The English introduced at February 25th, 1940 their summertime GMT+1. In the Netherlands we had Dutch Time.
This means that from February 25th, 1940 it was 40 min. later in England than in Holland. From may 16th, 1940 the
Germans introduced MET and the Dutch were one hour ahead of the English.
4) In England it was summertime during the war from February 25th, 1940 till October 7th, 1945.
5) To get more daylight went over to Double British Summertime(DBST). This was during:
a. 1941 May 4th till August 10th.
b. 1942 April 5th till August 9th
c. 1943 April 4th till August 15th
d. 1944 April 2nd till September 17th
e. 1945 April 2nd till July 15th
6) During these periods the time in England was GMT+2 and that’s the same as
MET(Summertime)
7) To make thing more clear some examples:
Date Time in Holland/Germany Time in England.
30-05-1940 12.28 11.28
22-06-1941 06.05 06.05
03-11-1942 14.18 14.18
01-04-1943 23.25 22.25
01-05-1943 20.08 20.08
06-06-1944 05.30 05.30
05-05-1945 08.00 09.00
8) The change of time was done in the early Sunday morning hours at 2.00 O’clock.
9) Here a list of dates were the German time was equal to British time.
a. 1941 May 4th till August 10th.
b. 1942 April 5th till August 9th and November 2nd till December 31.
c. 1943 January 1st till March 29th and April 4th till August 15th and from
October 4th till December 31st.
d. 1944 January 1st till April 2nd and April 4th till September 17th and October 2nd
till December 31st.
e. 1945 January 1st till April 2nd.
This is an translation of the essence of an article published in Bulletin Airwar 1939-1945 Nr.99. With many thanks
to Mr. Robert de Bruin, Great Bookham, England.
The translation has been made by Jaap Woortman."