Kew lookup please

[liza99]

Hi everybody

If someone is visiting Kew could they look up my ggrandfather for me in the
National Archives. His occupation was gunner in Royal Artillery when he married in St. Helier Jersey in 1868.

Info known :-
John Slater m. Elizabeth Trohear 13/9/1868 St Helier Jersey.
Cert.says age 29, gunner R.A., born Hartfield Sussex, father Samuel Slater blacksmith.
Birth cert for my gmother Elizabeth Mary Slater says b 18/7/1869 St. Helier, father John Slater occupation blacksmith.

John slater's wife remarried in Ulverston Lancs in mid 1872 so he must have died before then.

Any help with this much appreciated, as I am a long way from Kew and cannot visit myself. My sussex lookup hasn't found anything definite, so this is my last option.

Thanks
Liza