Hi, Roy.
As others have said, your grandfather's service records are the best place for details on him as an individual. All I can speculate on is that, as he was a Serjeant, he had seen either regular or territorial service before 1940.
BATTALION
To put him in a wider context, you'll need to find which battalion he served with. I think his number suggests he was a regular - do you know if that's the case? If so, he was likely with the 2nd Battalion, which was in France from 1939 until evacuation in 1940. A C Bell's "History of the Manchester Regiment, First and Second Battalions 1939-1945" will give you a good overview of the campaign.
If he wasn't with the 2nd, then the 5th, 8th (least likely as it sailed for Malta before Dunkirk) and 9th Battalions were also in France at that time. They were Territorial units, so if you think he had another job, are possible.
PHOTOGRAPHS
Always difficult to find these, though you could be lucky via the Manchester Regiment image archive. There are a couple of possible Howards in his time frame:
- Depot (1934) - if a regular.
https://manchester-regiment.org.uk/frontend.php?pos=2&action=zoom&keywords=Ref_No_increment;MATCHES;(^|%20+)MR01045($|%20+)&continueUrl=ZnJvbnRlbmQucGhwPyZrZXl3b3Jkcz1Ib3dhcmQmYWN0aW9uPXNlYXJjaA==
- Depot (1933)
https://manchester-regiment.org.uk/frontend.php?pos=3&action=zoom&keywords=Ref_No_increment;MATCHES;(^|%20+)MR01056($|%20+)&continueUrl=ZnJvbnRlbmQucGhwPyZrZXl3b3Jkcz1Ib3dhcmQmYWN0aW9uPXNlYXJjaA==
8th Bn (1940) -
https://manchester-regiment.org.uk/frontend.php?pos=9&action=zoom&keywords=Ref_No_increment;MATCHES;(^|%20+)MR03645($|%20+)&continueUrl=ZnJvbnRlbmQucGhwPyZrZXl3b3Jkcz1Ib3dhcmQmYWN0aW9uPXNlYXJjaA==
MEDALS
For the Second World War service you have outlined, he would have been awarded the 1939-1945 Star and War Medal. At 27, I don't think he'd have been old enough for a long service medal so, unless he spent time in Palestine with 1st Battalion, that could be his full entitlement. Again, the service records will tell you.
Hope that's a help. There's more digging you can do, but you'll need his unit first to make sure that's accurate.
All the best.