Find Ancestors

I wonder if anyone could possibly help me please? I'm trying to chase down information on my Grandfather JAMES WILLIAM WILSON - 1895-1957 with the ultimate aim of finding photographs of him. My Mother doesn't have a single photo of him as they were all left behind by her Mother when moving house, and as he died when she was only 11, (she's now 58,) she hasn't seen an image of him for a very long time. I would love to present her with a photograph of him but as I'm very new to geneology, I don't quite know where to start. Through surfing, I found that the Medal Rolls at the Public Record Office in Kew, London might be the best place to begin my search as my Grandfather was in WW1 though I don't know which regiment. I'm told he went to Egypt though this is unverified as yet. The following is as much as I know about him; Name: James William Wilson D.O.B. 03/10/1895 in No/42 Watson Street, Birkenhead, Wirral, England. Died: 07/11/1957 in the general hospital, Birkenhead. Father: William Wilson. (He was a Master Butcher and it states on his son's marriage certificate that he was dead by 1949.) Mother: Mary Hall. First wife was Margaret Love Watson. Married his second wife Margaret (known as Rita) Garrett on 18/06/1949 and they lived together in 385 New Chester Road, Birkenhead and later lived in 8 Coulthard Road, Birkenhead (his last address before death.) All the above information has been verified through various documents. I'm told he was a volunteer "fire-watcher" during WW2 since he was too old to enlist. And I've been told he also worked as a prison warden in Walton (Liverpool) for a time, living near the prison with his 1st wife but this information hasn't been verified yet. This is all the information I have on him, and as you can see it's not much. I just need a starting place... I would be grateful for any help or advice you can give me, and I thank you sincerely for your time. Yours faithfully, Miss. Ingrid Price.