It looks as though his service record has not survived*. There is a mention of him as Private T Berry, in the 1st Battalion of the Argyll and Sutherland Highlanders with the number S/20230, circa September 1918 on a casualty list (see image below). Because this was among the burnt documents in WO 363, there are no details about where he was, the exact date, or the severity of his injuries etc. He survived the war as he was transferred to the Class Z reserve on 22 May 1919. Class Z reserve meant that if hostilities resumed he could be recalled to the colours, so presumably whatever injuries he suffered in 1918 they weren't too serious.
As you are probably aware he first went to France on 18 Sep 1915 and so earned the 1914-15 Star as well as the Victory and British War medals.
The precise order of his service appears to be:
1914 enlisted in the 10th Battalion the Royal Highlanders (the Black Watch) with the number S/21138. Here's what the excellent website the Long, Long Trail has to say about this unit: "10th (Service) Battalion [of the Black Watch] Formed at Perth on 13 September 1914 as part of K3 and came under command of 77th Brigade in 26th Division.
Moved to Salisbury Plain, Bristol, Sutton Veny.
21 September 1915: Main body landed at Boulogne. Advance party had gone the day before."
Pte Thomas Berry then transferred to the Royal Army Medical Corps with the number 38329. It's not clear when this occurred, although the date he first went to France (Sep 1915) suggests that he was still with the 10th bn Black Watch.
Later still he transferred again to the Argylls with the number S/20230, which is the unit he was in at the end of the war.
* it is possible part or all of his record has survived among the burnt documents but because his regimental number(s) are obscured or missing his record doesn't come up in a general search. As you have probably seen there were dozens if not hundreds of Thomas or T Berrys who served in WW1.
