The tracer cards give a, sometimes confusing, outline of a man's whereabouts during the war. To be clear about the where and when of his service you need his service records which can be applied for:
https://www.gov.uk/get-copy-military-service-recordsIt looks as if he spent a good part of his service in 1 Air Landing Light Regiment which was glider-borne artillery support to 1 Airborne Division taking part, among other actions, the well known Operation Market Garden - Arnhem.
https://en.wikipedia.org/wiki/1st_Airlanding_Light_Regiment.
On the card you can ignore the entries like 1/43 and 10/43 to the left of each entry. These are the references of the piece of paper in the unit which recorded the event. The card starts in 1943 which with the attestation record which says he joined up again in 1938 suggests one before that – can’t tell.
7 Feb 1943 67 Medium Regiment – this regiment had two Suffolk batteries and was stationed in UK in 1943
17 Feb 1943 176 Field Regiment was in the UK in a “holding division” so a temporary posting
4 Mar 1943 1 Air Landing Light Regiment – went to N Africa then Italy then NW Europe
17 May 1943 Overseas (date agrees with N Africa arrival)
8 July 1943 X list (which implies a hospital stay)
6 August 1943 – (returns to) 1 Air Landing Light Regiment
10 Feb 1944 back to UK, still on the books of 1 Air Landing Light Regiment
16 Nov 1944 44 Reinforcement Holding Unit (RHU) (a temporary “marking time” posting while he waits for a new unit posting) – in NW Europe
17 Dec 1944 X list (in UK) another hospital stay
There is a gap here which should have an overseas move as he is next in 21 Army Group. This is essentially the whole of the army that was engaged from D Day until the end of the war in NW Europe – there is no indication which regiment he was with unless he remained with 1 Air Landing Light Regiment.
The remaining X list entries with 21 AG are short periods away from his unit which include hospital or awaiting postings – there is no unit detail. The X List 7 indicates working with another regiment. These entries don't quite add up as to where he was
54 RHU was also in NW Europe 2
12 Nov 1945 Y List (leave for release)
Class Z release 1 Feb 1946.
Tracer cards were maintained for the RA Record office not really for us to interpret 80 years later, and, believe or not, made sense to them as they had other records to cross check.
I do urge you if you can to apply for what looks like an interesting record.
MaxD