On the sleeper operated by Great Western or Scotrail?
On the Scotrail sleepers, I didn't think First class customers got free tea throughout the journey. Whether I've been in First or Standard I was given a pot (in First) and a cup (in Standard) in the morning only. When in the Lounge car travelling First class berths I have had to pay for tea, or have it deducted from the £5 catering voucher.
Stickers in the Lounge car say it is for First class berth customers only, with seats for those occupying Standard berths only where space is available.