Request re Rex AUTY's father 7th Anti Tank Regt WW2

From Rex AUTY :

Hello. My father was in 7th Anti Tank in WW2. I have his service records but find it difficult to discover exactly where they went to. I recall him
talking about the desert with  the 8th army & Monte Cassino but what about Crete? Service #20179 & #31011. Would it be possible to guide me as to where
to look.

Thanking you in advance.
Rex Auty