I was at Ty Croes for a brief stay in '79. We were actually at Valley for summer camp with cadets, but the cadets' accomodation was at Ty Croes which was otherwise almost deserted, there was a 'social club' but otherwise no catering, cadets having to be ferried to/from Valley by coach but there was also a small army (or was it or rock) presence for shooting at 300 yd from the clifftop
2 years earlier I had visited Benbecula from Farnborough and saw the CRP which was (I think) a Type 88 radar head to the north east of the airfield.