This multi isn't at the given co-ordinates, it will entail a short walk, you will need to visit three locations, Arch, Stones, Voices to gather the required info before the final location which can be found at...
51 04.ABC
001 09.DEF
First location - Arch.
During the First World War Folkestone became a major port of embarkation for millions of troops off to fight on foreign fields. The town became a staging post for not only British troops but for those from all over the commonwealth who had come to fight for the 'mother country'. The 'Step Short' memorial arch opened in 2014 as part of the commemorations marking 100 years since Britain joined World War 1 and remembers all who passed through the town on their way to the battlefields. The arch has been built close to the Road of Remembrance, formally 'The Slope' before it was renamed in the early 1920's and is named after the order given to the marching men to shorten their stride as they went downhill.
You are looking for
'run by sisters Margaret, Flora and Mrs Sturt' over ? men and women' first digit in five digit number = A.
'local man William Cotter of the Buffs died 191?' = B.
Second location - Stones.
This is a modern monument set in a large square of individually numbered pebbles dedicated to those who died on the first day of the Somme.
You are looking for
'a plaque that denotes the exact amount of British troops killed' second digit in five digit number = C.
Second digit minus 4th digit = D.
Third location - Voices.
An area of benches which have been transformed into an audio installation of voices reading letters sent to and from the servicemen fighting on the front line.
You are looking for
'a much loved man of Folkestone' letters in last name = E
First name minus letters in middle name = F.