LHR Clubhouse - busy on Saturdays

Looking to fly Man > LHR > DXB next June.
As we are only going to be flying economy, we usually like to get to the airport early to see if we can get any extra legroom seats, but as we will be connecting, this means that we will have to fly in from manchester a few hours earlier than necessary.
As we are booking through VH, I know we can buy Clubhouse access, so we may do this to while away the extra hours.
Now as it will be purchased through VH, am I right in thinking we can't pre-book beauty treatments, and it will be first come, first served on the day? If so, as we will be there saturday afternoon, how busy will the Clubhouse be, and what is the likelihood of me and my partner getting treatments. If it is going to be nigh on impossible, we may not bother as 60 pp is quite a bit not to experience the 'full' clubhouse.
As we are only going to be flying economy, we usually like to get to the airport early to see if we can get any extra legroom seats, but as we will be connecting, this means that we will have to fly in from manchester a few hours earlier than necessary.
As we are booking through VH, I know we can buy Clubhouse access, so we may do this to while away the extra hours.
Now as it will be purchased through VH, am I right in thinking we can't pre-book beauty treatments, and it will be first come, first served on the day? If so, as we will be there saturday afternoon, how busy will the Clubhouse be, and what is the likelihood of me and my partner getting treatments. If it is going to be nigh on impossible, we may not bother as 60 pp is quite a bit not to experience the 'full' clubhouse.