I'm ex Farnborough LARS (all sectors) now Fairoaks.
By all means phone Farnborough prior to the day to pre-warn them, but there could be a different watch in on saturday and sometimes essential info doesn't get passed on, so phone again on saturday (01252 526015) to confirm. Better still if your exercise is NOTAMMED as that'll give them something to refer to. There should be someone there from 0745 local time, but they'll be busy doing opening checks so better to wait until 8am before you phone.